Micro object detection apparatus

ABSTRACT

A micro object detection apparatus (11) includes an optical system (50). The first optical system (50) includes a first reflection region (101), a second reflection region (102), and a light reception element (6). The first reflection region (101) has an ellipsoidal shape, and reflects scattered light scattered when irradiation light hits a particle (R) to direct the scattered light to the light reception element (6), by utilizing two focal point positions of the ellipsoidal shape. The second reflection region (102) reflects scattered light coming from the particle (R) to direct the scattered light to the first reflection region (101), so that the scattered light is directed to the light reception element (6) by utilizing the ellipsoidal shape of the first reflection region (101). The light flux diameter of the scattered light reflected by the second reflection region (102) is larger than the particle (R), at the position of the particle (R) at which the scattered light is generated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of copending application Ser. No.15/772,405, filed on Apr. 30, 2018, which is the National Phase under 35U.S.C. § 371 of International Application No. PCT/JP2016/086550, filedon Dec. 8, 2016, which claims the benefit under 35 U.S.C. § 119(a) toPatent Application No. 2015-243250 filed in Japan on Dec. 14, 2015 andPatent Application No. 2016-017780, filed in Japan on Feb. 2, 2016, allof which are hereby expressly incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present invention relates to a micro object detection apparatus thathas a function for detecting a particle suspended in the air or aparticle suspended in liquid.

BACKGROUND ART

There are various proposals of a micro object detection. apparatus thatirradiates with light a space in which suspended micro particulatematter (hereinafter referred to as “particle(s)”) such as pollen or dustexists, detects scattered light generated at that time, and detects anamount of particles, the size of particles, kinds of particles, or thelike.

For example, patent reference 1 discloses a particle sensor thatincludes a light source, a light reception element, and convergingmirrors, to irradiate a particle with light emitted from the lightsource, reflect scattered light by the converging mirrors, and detectthe intensity of the scattered light by the light reception element.

In the particle sensor described in patent reference 1, the two oppositeconverging mirrors are an elliptical mirror and a spherical mirror. Apassage region where a particle that radiates scattered light passesthrough is located at the position of one focal point (first focalpoint) of the elliptical mirror. In addition, the light receptionelement for receiving the scattered light is located at the position ofthe other focal point (second focal point) of the elliptical mirror. Thefocal point (the center point of the curvature radius of a sphericalmirror surface) of the spherical mirror is positioned at the position ofthe first focal point of the elliptical mirror. Accordingly, it ispossible to further reflect the reflected light from the sphericalmirror by the elliptical mirror and to direct the reflected light to thelight reception element.

PRIOR ART REFERENCE Patent Reference

PATENT REFERENCE 1: WO2007-063862

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

However, the light reflected from the spherical mirror is againconverged to the particle. Hence, the light reflected from the sphericalmirror is blocked by the particle itself, and does not reach the lightreception element. This results in decrease in scattered light detectionefficiency. In addition, there is a problem that it becomes difficult todetect the particle in a detection circuit for detecting the particle onthe basis of an output signal from the light reception element.

Thus, the present invention is made to solve the above problem, of theconventional technology. Its purpose is to provide a micro objectdetection apparatus capable of preventing decrease in efficiency indetecting scattered light and improving accuracy in detecting theparticle, by reducing light blocking by a particle itself in a particlesensor that uses two opposite converging mirrors.

Means of Solving the Problem

The micro object detection apparatus according to the present inventionincludes a first optical system including a first reflection region, asecond reflection region, and a light reception element. The firstreflection region has an ellipsoidal shape, and reflects scattered lightscattered when irradiation light hits a particle, to direct thescattered light to the light reception element, by utilizing two focalpoint positions of the ellipsoidal shape. The second reflection regionreflects scattered light coming from the particle to direct thescattered light to the first reflection region, so that the scatteredlight is directed to the light reception element by utilizing theellipsoidal shape of the first reflection region. A light flux diameterof the scattered light reflected by the second reflection region islarger than the particle, at a position of the particle at which thescattered light is generated.

Effects of the Invention

As described above, according to the present invention, efficiency inreceiving, the scattered light from the particle and accuracy indetecting the particle can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram schematically illustrating aconfiguration of a micro object detection apparatus according to a firstembodiment of the present invention.

FIG. 2 is a configuration diagram, schematically illustrating theconfiguration of the micro object detection apparatus according to thefirst embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating a light beam on a firstpath in the micro object detection apparatus according to the firstembodiment of the present invention.

FIG. 4 is a diagram schematically illustrating a light beam on a secondpath in the micro object detection apparatus according to the firstembodiment of the present invention.

FIG. 5 is a diagram schematically illustrating a light beam on a thirdpath in the micro object detection apparatus according to the firstembodiment of the present invention.

FIG. 6 is a diagram schematically illustrating main scattered lightgenerated when a particle is irradiated with laser light.

FIG. 7 is a block diagram illustrating a detection circuit unit of themicro object detection apparatus according to the first embodiment ofthe present invention.

FIG. 8 is a diagram schematically illustrating a light beam on a thirdpath in a conventional micro object detection apparatus.

FIG. 9 is a diagram schematically illustrating a waveform of a detectionsignal in the conventional micro object detection apparatus.

FIG. 10 is a diagram schematically illustrating a waveform of adetection signal S₁ in the micro object detection apparatus according tothe first embodiment of the present invention.

FIG. 11 is a diagram schematically illustrating a light beam on thethird path in the micro object detection apparatus according to thefirst embodiment of the present invention.

FIG. 12 is a diagram schematically illustrating a light beam on thethird path in the micro object detection apparatus according to thefirst embodiment of the present invention.

FIG. 13 is a diagram schematically illustrating a light beam on thethird path in the micro object detection apparatus according to thefirst embodiment of the present invention.

FIG. 14 is a block diagram illustrating a detection circuit unit of amicro object detection apparatus according to a second embodiment of thepresent invention.

FIG. 15 is a configuration diagram schematically illustrating aconfiguration of a detection optical system of a micro object detectionapparatus according to a third embodiment of the present invention.

FIG. 16 is a configuration diagram schematically illustrating aconfiguration of an optical system of the micro object detectionapparatus according to the third embodiment, of the present invention.

FIG. 17 is a configuration diagram schematically illustrating aconfiguration of an optical system of the micro object detectionapparatus according to the third embodiment of the present invention.

FIG. 18 is a block diagram illustrating a detection circuit unit of themicro object detection apparatus according to the third embodiment ofthe present invention.

MODE FOR CARRYING OUT THE INVENTION

Regarding matter such as PM2.5 and PM10 also called micro particulatematter, since the light amount of scattered light is small, collectingthe scattered light by using a converging mirror is effective forincreasing the light amount. On the other hand, as for pollen, dust, orthe like, since particle diameters are large, collecting scattered lightis less effective than the micro particulate matter.

A patent reference, Japanese Patent Application Publication No.2004-125602, describes a pollen sensor that measures the intensity ofpolarized light in a direction parallel to irradiation light from alight emitting unit and the intensity of polarized light in a directionperpendicular to the irradiation light from the light emitting unit,among scattered light from a suspended particle, and distinguishesbetween a suspended particle of pollen and a suspended particle otherthan pollen. Moreover, each of light receiving units for receiving thescattered light is located in a direction of scattered light of 60° fromthe incident light axis of the irradiation light.

However, in an optical system for collecting scattered light by using aconverging mirror and the like, when the scattered light is reflected inan oblique direction by the converging mirror, the optical system isaffected by change in polarization direction and change in reflectanceand it causes reduction in accuracy in detecting polarized lightcomponent. Thus, it is difficult to detect micro particulate matter andpollen by using one optical system.

Moreover, for example, in the case of an optical system that uses anelliptical mirror and a spherical mirror as in patent reference 1, aparticle at which scattered light is generated is a light blockingobject, for scattered light reflected by the spherical mirror. By thislight blocking of the scattered light, one peak of a detection signalcorresponding to one particle is changed into two peaks. Hence, there isa problem that erroneous detection of miscounting the number ofparticles occurs.

To facilitate explanation, coordinate axes of an xyz-rectangularcoordinate system are illustrated in each of the drawings. In thefollowing description, the direction linking the center of a suctionport 5 a and the center of a discharge port 5 b in a micro objectdetection apparatus 11 is set as an x axis direction. The suction port 5a side is a +x axis direction. The discharge port 5 b side is a −x axisdirection. The direction linking the center of a first converging mirror101 and the center of a second converging mirror 102 is set as a y axisdirection. The first converging mirror 101 side is a +y axis direction.The second converging mirror 102 side is a −y axis direction. Thedirection in which irradiation light 3 is radiated is set as a z axisdirection. The direction in which the irradiation light 3 travels is a+z axis direction. The side on which a laser light emitting element 1 islocated is a −z axis direction.

For example, in the case of patent reference 1, a y axis is parallel toa line segment linking a first focal point and a second focal point ofthe elliptical mirror. Moreover, the y axis is an axis perpendicular toa z-x plane.

First Embodiment

FIGS. 1 and 2 are configuration diagrams schematically illustrating aconfiguration of an optical system 500 of a micro object detectionapparatus 11 according to a first embodiment of the present invention.FIG. 1 is a configuration diagram illustrating a y-z cross section ofthe optical system 500 of the micro object detection apparatus 11. FIG.2 is a configuration diagram illustrating a z-x plane of the opticalsystem 500 of the micro object detection apparatus 11.

<Optical System 500 of Micro Object Detection Apparatus 11>

As illustrated in FIGS. 1 and 2, the optical system 500 of the microobject detection apparatus 11 includes a detection optical system 50 asa main component. The optical system 500 of the micro object detectionapparatus 11 can include a laser light emitting element 1 or a lens 2.In addition, the optical system 500 of the micro object detectionapparatus 11 can include a beam trap 4 or a radiation unit holder 91.

The detection optical system 50 includes a first converging mirror 101,a second converging mirror 102, and a light reception element 6.

A laser light radiation unit 10 includes the laser light emittingelement 1. In addition, the laser light radiation unit 10 can includethe lens 2 or the radiation unit holder 91.

The laser light emitting element 1 is a light source. The lens 2 directslight emitted from the laser light emitting element 1 to a detectionregion D.

In the first embodiment, a light source is described as a laser lightsource. However, the light source may be an LED or the like, forexample. In this case, the irradiation light 3 is LED light or the like.Moreover, the irradiation light 3 may be monochromatic light, or maywhite light. The laser light emitting element 1 emits the irradiationlight 3.

The lens 2 transmits the light emitted from the laser light emittingelement 1, as irradiation light for irradiating a detection targetparticle H. The lens 2 transmits the irradiation light 3 emitted fromthe laser light emitting element 1 to the detection region D.

In the first embodiment, the laser light (the irradiation light 3)emitted from the laser light emitting element 1 is incident on the lens2. The lens 2 converges the entering laser light (the irradiation light3), for example. Alternatively, the lens 2 converts the entering laserlight (the irradiation light 3) to parallel light, for example. The lens2 changes a divergence angle of the entering laser light (theirradiation light 3).

The laser light (the irradiation light 3) coming from the lens 2 isdirected to the detection region D by the lens 2. The laser light (theirradiation light 3) directed to the detection region D is in aconverged light state or a parallelized light state, for example. Thelens 2 may be a cylindrical lens or a toroidal lens that has a lightconverging function, for example.

The suspended particle R exists in the detection region D. The lens 2can be removed in a case such as when the intensity of the irradiationlight 3 can be set sufficiently large for the detection of the suspendedparticle R.

The radiation unit holder 91 holds the laser light emitting element 1and the lens 2, for example. The radiation unit holder 91 combines thelaser light emitting element 1 and the lens 2 as one unit.

The radiation unit holder 91 is attached to the first converging mirror101 or the second converging mirror 102, for example in FIG. 1, theradiation unit holder 91 is attached to the first converging mirror 101and the second converging mirror 102, for example.

The particle R is micro particulate matter suspended in the air, asdescribed above. The suspended particle R of the detection targetincludes pollen, dust, cigarette smoke, or the like. The particle R ispollen, dust, or the like, for example. The dust is referred to as housedust. In addition, the particle R includes dead bodies, their brokenpieces and excretion of minute creatures such as mites, and the like. Inaddition, the particle R includes what is called micro particulatePM2.5, micro particulate matter PM10, or the like. PM2.5 is a smallparticle having a particle size of 2.5 μm or less, among small particlessuspended in the air. The ingredients of PM2.5 include inorganicelements, such as carbon, nitrate, sulfate, ammonium salt, silicon,sodium, or aluminum. PM10 is a small particle having a particle size of10 μm or less, among small particles suspended in the air.

PM2.5 and PM10 are also referred to as micro particulate matter. The“particulate matter” means micrometer-size solid or liquid fineparticles.

The particle R is irradiated with the irradiation light 3. In this case,scattered light L is generated from the particle R.

The “scattered light” is light generated when the irradiation light 3hits the suspended particle R and its propagation state is changed. The“propagation” means that a wave spreads in a medium. Here, the“propagation” means that light travels in a space. The term space means,as described above, in the air, in a liquid, in a vacuum, or the likehowever, the “scattered light” includes fluorescence of the suspendedparticle R generated by the wavelength of the irradiation light 3.

The detection target particle R is not limited particularly, if it isminute matter that generates the scattered light L when irradiated withthe irradiation light 3.

The detection optical system 50 includes the first converging mirror101, the second converging mirror 102, and the light reception element6. The detection optical system 50 is also referred to as a scatteredlight receiving unit.

The first converging mirror 101 and the second converging mirror 102direct part of the scattered light L to the light reception element 6.The first converging mirror 101 is an elliptical mirror, for example.The second converging mirror 102 is a spherical mirror, for example. Thefirst converging mirror 101 and the second converging mirror 102 may beregions that are part of one converging mirror.

Here, the elliptical mirror is not needed to have an ideal ellipsoidalshape. Here, the elliptical mirror is a mirror having a function forcollecting light that diffuses from a certain point to another point byits reflection, and is an elliptical mirror in a broad sense. Note thatthe other point to which the light is collected may be an area having acertain size.

A light beam that passes through one focal point of two focal points ofan ellipse is reflected by an elliptical surface, and passes through theother focal point. The elliptical surface is a quadric surface whosecross-section cut by a plane parallel to three coordinate planes isalways an ellipse.

The first converging mirror 101 reflects scattered light 111 a that isincident directly from the particle R, to direct the scattered light tothe light reception element 6, by utilizing the positions of the twofocal points of the ellipse. For example, the suction port 5 a and thedischarge port 5 b guide the particle R to the position of one focalpoint. (a first focal point) of the first converging mirror 101. Thelight reception element 6 is located at the position of the other focalpoint (a second focal point) of the first converging mirror 101.

The irradiation light 3 hits the particle R in the region of the onefocal point (the first focal point). The region in which the irradiationlight 3 crosses the passage region P includes the first focal point ofthe first converging mirror 101.

The light reception element 6 detects the intensity of the scatteredlight L. That is, the light reception element 6 is a light detector. Thelight reception element 6 is a photo diode or the like, for example.

The light reception element 6 outputs an electric current or voltagecorresponding to the intensity of the light. The light reception element6 includes a light reception region for receiving the light. The lightreception element 6 receives the scattered light L.

When the output of the light reception element 6 is an electric current,the micro object detection apparatus 11 can include an IV conversioncircuit (current-voltage conversion circuit) for converting a currentvalue to voltage, at a stage subsequent to the light reception element6.

On the other hand, when the output of the light reception element 6 isvoltage, the micro object detection apparatus 11 can include a buffercircuit at the stage subsequent to the light reception element 6, inorder to convert the voltage to stable voltage. The buffer circuit is avoltage follower or the like, for example.

The suction port 5 a is a suction nozzle, for example. The dischargeport 5 b is a discharge nozzle, for example. The suction port 5 a guidesthe air or a liquid test object containing the detection target particleR to the detection region D. Moreover, the discharge port 5 b dischargesthe air or a liquid test object containing the detection target particleR from the detection region D. The passage region P where the particle Rpasses through is formed between the suction port 5 a and the dischargeport 5 b.

Note that the irradiation light 3 radiated from the laser light emittingelement 1 is needless to be orthogonal to a straight line that passesthrough the suction port 5 a and the discharge port 5 b, for example.That is, the irradiation light 3 radiated from the laser light emittingelement 1 is needless to be orthogonal to the direction in which theparticle R flows from the suction port 5 a to the discharge port 5 b.That is, the irradiation light 3 radiated from the laser light emittingelement 1 can be radiated on the particle R at an inclined anglerelative to the direction in which the particle R flows from the suctionport 5 a to the discharge port 5 b.

The liquid test object refers to a liquid that contains the detectiontarget particle R.

The detection region D is the region surrounded by the first convergingmirror 101 and the second converging mirror 102.

For example, the detection region D is a region in a gas, such as air.Alternatively, the detection region D is a region in a liquid, such aswater. Alternatively, the detection region D is a vacuum region.

The detection target particle R passes through the detection region D.In the first embodiment, the particle R passes through the detectionregion D from the +X axis side toward the −X axis side. For example, theparticle R is suspended in the air. Alternatively, the particle R iscontained in the liquid.

The particle R passage region P in the detection region D may be aregion closed by a wall or the like that allows the irradiation light 3to transmit. Alternatively, the passage region P where the particle Rpasses through in the detection region D may be an open region.

That is, the irradiation light 3 passes through the wall that surroundsthe passage region P. The passage region P is a region through which theparticle R passes from entering the detection region D until exiting thedetection region D. In the first embodiment, the particle R enters thedetection region D from the suction port 5 a. The particle R exits thedetection region D from the discharge port 5 b.

The beam trap 4 prevents the irradiation light 3 that has exited thepassage region. P where the particle R passes through from beingreflected and returning to the passage region P. The beam trap 4 trapslight, absorbs light, or releases light to the outside of the detectionregion D.

That is, the beam trap 4 transmits light to the outside of the detectionregion D. The beam trap 4 prevents light from entering the detectionregion D again.

<Relationship between Scattered Light L and Light Reception Element 6>

A relationship between the scattered light L and the light receptionelement 6 in the detection region D in the micro object detectionapparatus 11 according to the first embodiment will be described.

In the detection optical system 50 of the micro object detectionapparatus 11 according to the first embodiment, there are three types ofpaths leading the scattered light L generated at the particle R to thelight reception element 6.

The scattered light L is generated at the particle R. The scatteredlight L is directed to the light reception element 6 by the detectionoptical system 50. There are three types of paths to the Light receptionelement 6.

FIGS. 3, 4, and 5 are diagrams schematically illustrating the paths ofthe light beam in the micro object detection apparatus 11. FIG. 3illustrates a first path. FIG. 4 illustrates a second path. FIG. 5illustrates a third path. FIGS. 3, 4, and 5 illustrate onlyrepresentative light beams of the scattered light L, to reduce thecomplexity of the drawings.

In FIG. 3, the scattered light L (a light beam 111 a) scattered by theparticle R reaches the first converging mirror 101. When reaching thefirst converging mirror 101, the scattered light L (the light beam 111a) is reflected by the first converging mirror 101. After the reflectionby the first converging mirror 101, the scattered light L (a light beam111 b) reaches the light reception element 6. In the following, thispath is referred to as the first path. The scattered light L representedas the first path is referred to as the light beams 111 a, 111 b.

FIG. 3 illustrates the behavior of the light beams, by using the lightbeams 111 a, 111 b that are representative light beams of the scatteredlight L. The light beam 111 a is a light beam of the scattered light Lfrom the particle R and is incident on the first converging mirror 101.The light beam 111 b is a light beam of reflected light obtained whenthe light beam 111 a is reflected by the first converging mirror 101.The reflected light 111 b directed to the light reception element 6.

In FIG. 4, the scattered light L (the light beam 112) scattered by theparticle R reaches the light reception element 6 directly. That is, thescattered light L (the light beam 112) is not reflected by the firstconverging mirror 101 or the second converging mirror 102. In thefollowing, this path is referred to as the second path.

FIG. 4 illustrates the behavior of the light beam, with the light beam112 that is a representative light beam of the scattered light L. Thelight beam 112 is a light beam of the scattered light L that directlyreaches the light reception element 6 from the particle R. Thus, thelight beam 112 reaches the light reception element 6, without reachingthe first converging mirror 101 or the second converging mirror 102.

In FIG. 5, the scattered light L (light beam 113 a) scattered at theparticle R reaches the second converging mirror 102. The scattered lightL (light beam 113 a) that has reached the second converging mirror 102is reflected by the second converging mirror 102. The scattered light L(light beam 113 b) reflected by the second converging mirror 102 reachesthe first converging mirror 101. The scattered light L (light beam 113c) that, has reached the first converging mirror 101 is reflected by thefirst converging mirror 101. Note that the light beam 113 c is the samelight beam as the light beam 113 b. The scattered light L (light beam113 d) reflected by the first converging mirror 101 reaches the lightreception element 6. In the following, this path is referred to as thethird path.

FIG. 5 illustrates the behavior of the light beams, by using the lightbeams 113 a, 113 b, 113 c, and 113 d that are representative light beamsof the scattered light L. The light beam 113 a is a light beam of thescattered light L that travels toward the second converging mirror 102from the particle R. The light beam 113 b is a light beam of reflectedlight obtained when the light beam 113 a of the scattered light. L isreflected by the second converging mirror 102. The light beam 113 c is alight, beam when the reflected light 113 b is incident on the firstconverging mirror 101. That is, the light beam 113 c and the light beam113 b are the same light beam. The light beam 113 d is a light beam ofreflected light obtained when the light beam 113 c is reflected by thefirst converging mirror 101. The light beam 113 d is directed to thelight reception element 6. In the following, the light beams 113 b, 113d are also referred to as reflected light.

That is, the light beams 113 a, 113 b, 113 c, and 113 d can be describedas below. The light beam 113 a is the light beam that reaches the secondconverging mirror 102 from the particle R. The light beam 113 b is thelight beam that is reflected by the second converging mirror 102 andreaches the passage region P. That is, the light beam 113 b is the lightbeam that returns to the original position of the particle R from thesecond converging mirror 102. The light beam 113 c is the light beamthat reaches the first converging mirror 101 from, the passage region P.The light beam 113 d is the light beam, that is reflected by the secondconverging mirror 102 and reaches the light reception element 6.

The above configuration of the detection optical system 50 of the microobject detection apparatus 11 according to the first embodiment differsfrom the configuration disclosed in prior reference 1. The shape of thesecond converging mirror 102 according to the first embodimentproactively generates aberration at the focal point position, unlike theshape of the spherical mirror disclosed in prior reference 1.

The light flux diameter of the scattered light reflected by the secondconverging mirror 102 is larger than the particle diameter of theparticle R, at the position of the particle R at which the scatteredlight is generated.

The light flux diameter of the scattered light reflected by the secondconverging mirror 102 is larger than the light flux diameter of thescattered light reflected by the converging mirror in the case of thesecond converging mirror 102 having a spherical shape, at the positionof the particle R at which the scattered light is generated. The secondconverging mirror 102 is an aspherical mirror based on this sphericalshape, for example. The spherical shape approximates the asphericalshape of the second converging mirror 102, for example. The secondconverging mirror 102 generates a plurality of focal points anddisperses those focal points, for example. Moreover, the secondconverging mirror 102 generates spherical aberration, for example. Thesecond converging mirror 102 generates larger aberration than aberrationthat remains when manufactured as a spherical mirror, for example.

In general, the concentrated light has the spherical aberration smallerthan 0.07 λrms, for example. Hence, the collected light collected by thesecond converging mirror 102 has the spherical aberration equal to orlarger than 0.07 λrms.

Moreover, the shape of the second converging mirror 102 is the shapethat proactively generates the aberration at the focal point position.Hence, the shape of the second converging mirror 102 is an asphericalshape, for example. That is, the spherical shape of the secondconverging mirror 102 is changed to the aspherical shape.

Then, the aberration generated by the second converging mirror 102 islarger than the aberration generated by the spherical mirror thatapproximates the aspherical shape of the second converging mirror 102.That is, the second converging mirror 102 generates larger aberrationthan the aberration generated by the original spherical mirror.

This second converging mirror is different, and thereby the efficiencyin detecting the scattered light L improves, as described later.Moreover, the accuracy in detecting number concentration or weightconcentration of the particle R can be improved. The “numberconcentration.” represents the number of particles per unit volume. The“weight concentration.” represents the weight of particles per unitvolume.

<Type of Scattered Light>

FIG. 6 is a diagram schematically illustrating main scattered light Lgenerated when the particle R is irradiated with the irradiation light3. The irradiation light 3 is laser light, for example.

The irradiation light 3 is light emitted from the laser light emittingelement 1, in the first embodiment. The scattered light L is lightscattered when the irradiation light 3 hits the particle R.

Scattered light Lbs is light traveling toward the direction (−z axisdirection) of the laser light emitting element 1. The scattered lightLbs is light (returning light) returning in the direction (−z axisdirection) of the laser light emitting element 1. That is, the scatteredlight Lbs is light traveling backward. The “backward” means the oppositedirection (−z axis direction) to the direction in which the light isemitted from the laser light emitting element 1 (+z axis direction).

Scattered light Lfs is light traveling forward (+z axis direction). The“forward.” means the direction in which the light is emitted from thelaser light emitting element 1 (+z axis direction).

Scattered light Ls is light traveling laterally. The “laterally” means adirection perpendicular to the direction (+z axis direction) in whichthe light is emitted from the laser light emitting element 1. That is,the “laterally” means a direction on a plane (x-y plane) perpendicularto the direction (+z axis direction) in which the light is emitted fromthe laser light emitting element 1. However, the traveling direction ofthe light beam may incline relative to the z axis. The scattered lightLs illustrated in FIG. 6 travels with an inclination in the +z axisdirection.

That is, the scattered light Ls is light that travels with aninclination to the direction in which the irradiation light 3 travels.For example, assuming that the irradiation light 3 travels along theaxis of a cylinder, the scattered light Ls is a light beam that passesthrough the side surface of the cylinder. Here, the cylinder used in thedescription is an imaginary cylinder. Laterally means a direction otherthan forward and backward.

The light beams 111 a, 112, 113 a illustrated in FIGS. 3, 4, and 5 arethe scattered light Ls.

Here, explanation of general scattering will be given. In general, whenthe particle R is irradiated with the irradiation light 3 having awavelength comparatively close to the size of the particle R, thescattered light is generated. The irradiation light 3 is not limited tolaser light particularly.

The scattered light L is roughly classified into two types of light. Oneis the forward scattered light Lfs. The other is scattered light otherthan the forward scattered light Lfs. The forward scattered light Lfs isgenerated in a direction in which the irradiation light 3 propagates (+zaxis direction). The scattered light generated in a direction other thanthe direction in which the irradiation light 3 propagates is, forexample, the backward scattered light Lbs or the lateral scattered lightLs.

The proportion of the intensity of the scattered light changes,according to the shape and the size of the particle R. The intensitydistribution (distribution of the scattering intensity) of the scatteredlight traveling from the particle R toward each direction changes,according to the shape and the size of the particle R.

For example, as the size (for example, diameter) of the particle Rbecomes larger, the intensity of the scattered light L becomes greater.The intensity of the scattered light L is far smaller than the intensityof the irradiation light 3. As part of the scattered light L, there isthe backward scattered light Lbs traveling toward the direction (−z axisdirection) opposite to the traveling direction of the irradiation light3 (+z axis direction).

<Detection Circuit Unit 60>

Next, the configuration other than the detection optical system 50 willbe described. FIG. 7 is a block diagram illustrating a detection circuitunit 60 of the micro object detection apparatus 11 according to thefirst embodiment of the present invention.

The micro object detection apparatus 11 according to the firstembodiment can employ the detection circuit unit 60. The detectioncircuit unit 60 is effective to prevent a negative effect of quasi peakdescribed later. However, when the quasi peak is prevented by thedetection optical system 50 described in the first embodiment, it is notnecessary for the micro object detection apparatus 11 to use thedetection circuit unit 60. On the other hand, the detection circuit unit60 is effective when used in a conventional detection optical system 51.

Note that a current-voltage conversion unit for converting an outputcurrent value from the light reception element 6 to a voltage value willbe omitted here.

The detection circuit unit 60 includes a peak number counter 63. Thedetection circuit unit 60 can include an amplifier circuit 61 or amaximum, peak detector 62.

The amplifier circuit 61 amplifies or attenuates the level of an outputsignal S₁ from the light reception element 6. The amplifier circuit 61outputs a signal S₂. The amplifier circuit 61 can be removed when asufficient signal level is satisfied in the subsequent processing, forexample.

The signal S₂ is obtained by amplifying or attenuating the level of theoutput signal S₁.

The maximum peak detector 62 receives the output signal S₂. The maximumpeak detector 62 detects a maximum peak point of the output signal S₂from the amplifier circuit 61. The maximum peak point of the outputsignal S₂ corresponds to the particle R. The maximum peak detector 62sequentially processes the detection of the maximum peak point of theoutput signal S₂. Note that the maximum peak detector 62 can be removedwhen the number of particles R can be counted by using a threshold valueor the like, without detecting the maximum peak point, for example.

The maximum peak detector 62 outputs a signal S₃. The signal S₃indicates the maximum, peak point of the output signal S₂.

The peak number counter 63 receives the signal S₃ indicating the maximumpeak point output by the maximum peak detector 62. The peak numbercounter 63 counts the number of peaks corresponding to the detection ofthe particle R. The peak number counter 63 is the counter that countsthe number of peaks of the signal S₃. Alternatively, the peak numbercounter 63 is a particle number counter that counts the number ofparticles by counting the number of peaks of the signal S₃.

The number concentration or the weight concentration of the particles Rcan be calculated by using the count value of the number of peaksobtained by the peak number counter 63 of the detection circuit 60. Themicro object detection apparatus 11 calculates the number concentrationor the weight concentration of the particles R, by using the count valueof the number of peaks.

<Feature and Effect of Second Converging Mirror 102>

Next, features and effects of the second converging mirror 102 in themicro object detection apparatus 11 according to the first embodimentwill be described.

A conventional micro object detection apparatus will be described byusing FIGS. 8 and 9, in order to describe the features of the secondconverging mirror and resulting effects in the micro object detectionapparatus 11 according to the first embodiment.

FIG. 8 is a diagram schematically illustrating a light, beam on a thirdpath in the detection optical system 51 of the conventional micro objectdetection apparatus. FIG. 9 is a diagram schematically illustrating awaveform of a detection signal S₁ of the conventional micro objectdetection apparatus. FIG. 10 is a diagram schematically illustrating awaveform of the detection signal S₁ of the micro object detectionapparatus 11 according to the first embodiment.

FIG. 8 corresponds to FIG. 5 illustrating the micro object detectionapparatus 11. Thus, the same reference signs are assigned the samecomponents and light beams as in FIG. 5. The description of FIG. 5 issubstituted for the description of them.

In FIGS. 9 and 10, the vertical axis represents output values A of thedetection signal S₁, and the horizontal axis represents time (msec).

The conventional micro object detection apparatus differs from the microobject detection apparatus 11 according to the first embodiment, in theshape and the function of the second converging mirror 102.

That is, the conventional micro object detection apparatus differs fromthe micro object detection apparatus 11 according to the firstembodiment, in the shape of the second converging mirror 102 inaddition, the conventional micro object detection apparatus differs fromthe micro object detection apparatus 11 according to the firstembodiment, in the function of the second converging mirror 102.

In the second converging mirror 104 according to the conventional microobject detection apparatus, the reflection surface has a sphericalshape. The focal point of the second converging mirror 104 according tothe conventional micro object detection apparatus is identical with onefocal point (the first focal point) of the first converging mirror 103.As described above, the particle R is guided to the position of thefirst focal point.

As described above, the first converging mirror 103 is an ellipticalmirror. For example, the first converging mirror 103 has the shape of aspheroid. The elliptical mirror is a mirror surface having a surfacethat reflects the light radiated from one focal point (the first focalpoint) to collect the light into the other focal point (the second focalpoint) by utilizing two focal points that are characteristics of anellipse.

The scattered light L (the light beam 113 a) scattered at the particle Rreaches the second converging mirror 104. The scattered light L (thelight beam 113 a) that has reached the second converging mirror 104 isreflected by the second converging mirror 104. Then, the scattered lightL (the light beam 113 b) reflected by the second converging mirror 104returns to the position of the first focal point (the position of theparticle R) again.

Hence, the reflected light 113 b of the second converging mirror 104travels the completely same path as the first path. The first path is apath for a right beam of the scattered light generated at the particle Rthat is incident on the first converging mirror 103 and then directed tothe light reception element 6. The light beam of the scattered light Lgenerated at the particle R that is incident on the first convergingmirror 103 and then directed to the light reception element 6 is thelight beams 111 a, 111 b illustrated in FIG. 3.

Thereby, the detection optical system 51 can collect both of thescattered light L on the third path and the scattered light L on thefirst path, at the light receiving surface of the light receptionelement 6.

However, when the particle R passes through the position of the focalpoint of the second converging mirror 104, the particle R itself becomesa light blocking object on the third path. That is, the light beam 113 breflected by the second converging mirror 104 is blocked by the particleR. Thus, the detection optical system 51 is unable to direct thescattered light L blocked by the particle R, to the light receptionelement 6. This decreases the efficiency in detecting the scatteredlight L from the particle R. In addition, the accuracy in detecting theparticle R in the detection circuit unit 60 decreases.

The scattered light blocked by the particle R sometimes travels in adirection other than the reflection surface of the first convergingmirror 103 and the second converging mirror 104, for example. An exampleis the direction of the suction port 5 a or the discharge port 5 b.Another example is the direction of the laser light emitting element 1or the beam trap 4.

FIG. 9 is a diagram schematically illustrating a waveform F₁ of thedetection signal S₁ when one particle R passes through the position ofthe focal point, in the case of the conventional micro object detectionapparatus. The waveform F₁ of the detection signal S₁ in the case of theconventional micro object detection apparatus is indicated by a solidline in FIG. 9. A waveform F₂ of an ideal detection signal is indicatedby dashed line in FIG. 9.

The particle R itself blocks the scattered light L, and thereby thesignal S₁ drops at the center (t=tc) of the waveform F₁ of the detectionsignal S₁.

Moreover, the waveform F₂ indicated by the dashed line in FIG. 9 is thedetection signal S₁ obtained when the scattered light L generated at theparticle R is ideally detected without being influenced by blocking theparticle R. In the waveform F₂ of the ideal detection signal S₁, onemaximum peak point Ap corresponds to one particle.

On the other hand, in the waveform. F₁ of the detection signal S₁indicated by the sold line in FIG. 9, there are two maximum peak pointsAp₁, Ap₂ for one particle R. There is a minimum peak point Ap₃ at whichthe output value decreases, between the two maximum peak points Ap₁,Ap₂. In this case, a problem of an error in the number of counts ariseswhen the number of peaks is counted by the detection circuit unit 60illustrated in FIG. 7, for example.

That is, the detection circuit unit 60 miscounts one particle R as twoparticles. The detection circuit unit 60 counts one particle R at themaximum peak point Ap₁. In addition, the detection circuit unit 60counts one particle R at the maximum peak point Ap₂. A plurality of peaksignals are thus generated with respect to one particle R when light isblocked, for example, and such peak signals are referred to as quasipeaks.

The maximum peaks Ap₁, Ap₁ and the minimum peak point Ap₃ are theextreme values of the input signal S₂ corresponding to the particle (R).The maximum peaks Ap₁, Ap₂ are the local maximum values of the inputsignal S₂ corresponding to the particle (R). The minimum peak point Ap₃is the local minimum value of the input signal S₂ corresponding to theparticle (R). When the input signal S₂ is a continuous function, a pointat which the input signal S₂ changes from increasing to decreasing isreferred to as local maximum. Moreover, a point at which the inputsignal S₂ changes from decreasing to increasing is referred to as localminimum. The value of the input signal S₂ at a local maximum is a localmaximum value. The value of the input signal S₂ at a local minimum is alocal minimum value.

In FIG. 9, the output value at the maximum peak point Ap₁ is a peakvalue P₁. Moreover, the output value at the maximum peak point Ap₂ is apeak value P₂. Moreover, the output value at the minimum peak point Ap₃is a peak value P₃. The difference between the peak values P₁, P₂ andthe peak value P₃ is a value ΔP₁.

In contrast, a waveform F₃ of the detection S₁ in the micro objectdetection apparatus 11 according to the first embodiment will bedescribed.

FIG. 10 is a diagram schematically illustrating a waveform F₃ of thedetection signal S₁ when one particle R passes through the focal pointposition, in the case of the micro object detection apparatus 11according to the first embodiment. The waveform F₃ of the detectionsignal S₁ in the case of the micro object detection apparatus 11 isindicated by a solid line in FIG. 10. In addition, the waveform F₂ ofthe deal detection signal is indicated by a dashed line in FIG. 10, inthe same way as FIG. 9.

There are two maximum peak points Ap₄, Ap₅ for one particle R, in thewaveform F₃ of the detection signal S₁ indicated by the solid line inFIG. 10. There is a minimum peak point Ap₃ at which the output valuedecreases, between the two maximum peak points Ap₄, Ap₅.

In FIG. 10, the output value at the maximum peak point Ap₄ is a peakvalue P₄. The output value at the maximum peak point Ap₅ is a peak valueP₅. The output value at the minimum peak point Ap₆ is a peak value P₆.The difference between the peak values P₄, P₅ and the peak value P₆ is avalue ΔP₂.

The value ΔP₂ of the waveform F₃ illustrated in FIG. 10 is smaller thanthe value ΔP₁ of the waveform F₁ illustrated in FIG. 9. The value ΔP₁ isthe difference between the maximum peak points Ap₁, Ap₂ and the minimumpeak point Ap₃. The value ΔP₂ is the difference between the maximum peakpoints Ap₄, Ap₅ and the minimum peak point Ap₆.

Hence, a threshold value for counting the number of peaks can be sethigh. That is, miscounting due to noise can be reduced.

That is, the micro object detection apparatus 11 according to the firstembodiment, can reduce miscounting of the number of peaks due to noise,as compared with the conventional micro object detection apparatus.

In FIG. 9, the value ΔP₁ is a value obtained by subtracting the peakvalue P₃ at the minimum peak point Ap₃ from the average value of thepeak value P₁ at the maximum peak point Ap₁ and the peak value P₂ at themaximum peak point Ap₂, for example. Similarly, in FIG. 10, the valueΔP₂ is a value obtained by subtracting the peak value P_(E) at theminimum peak point Ap₆ from the average value of the peak value P₄ atthe maximum peak point. Ap₄ and the peak value P₅ at the maximum peakpoint Ap₅, for example.

The reflection surface of the second converging mirror 102 of the microobject detection apparatus 11 according to the first embodiment has anaspherical shape. This aspherical shape has a function for generatingaberration proactively.

In usual, the reflection surface is formed in an aspherical shape toprevent the aberration of the spherical mirror. The second convergingmirror 102 of the micro object detection apparatus 11 has an asphericalshape to generate the aberration. Hence, the second converging mirror102 of the micro object detection apparatus 11 generates largeraberration than the spherical mirror that approximates the asphericalshape, for example.

A least squares method or the like is used for the approximation of theaspherical shape, for example.

Moreover, when the light collection position of the second convergingmirror 102 has the aberration, the light flux diameter of the light thatreaches the light reception element 6 becomes larger. Hence, it isdesirable that the aberration at the light collection position of thesecond converging mirror 102 be within the extent that the lightreaching the light reception element 6 is received by the lightreceiving surface. Thereby, decrease in receiving efficiency of thelight reception element 6 can be prevented.

In the following, a case in which this aberration is sphericalaberration will be described, for example.

Spherical aberration is aberration with which an image is not formed atan ideal focal point position when the light is not a paraxial lightbeam. That is, the focal point position of a light beam away from adesign center axis O is different from the focal point position of alight beam (paraxial light beam) in the vicinity of the design centeraxis O of the second converging mirror 102. Aberration other thanchromatic aberration occurring due to color difference is referred to asspherical aberration in a broad sense. Note that, in the following, thespherical aberration is used in a narrow sense.

The paraxial light beam is a light beam passing through the vicinity ofthe optical axis and forming a small angle with the optical axis, in anoptical image formation system such as a lens or a spherical mirror. Thesmall angle is a small angle of the level that sine can be approximatedto angle θ (sin θ≈θ).

Here, in the configuration of the micro object detection apparatus 11, alight passage hole H is provided on the design center axis O of thesecond converging mirror 102. As illustrated in FIG. 5, a position G₁ isan innermost circumferential position of the reflection surface 102 a.Moreover, a position. G₂ is an outermost circumferential position of thereflection surface 102 a. In FIGS. 1, 3, 4, and 5, the center axis O isillustrated as an imaginary axis.

In the second converging mirror 102, the focal point position of theright beam reflected at the outermost circumferential position G₂differs from the focal point position of the light beam reflected at theinnermost circumferential position G₁.

This is because the second converging mirror 102 has an asphericalshape, as described above.

In order to achieve the second converging mirror 102 having thespherical aberration, the reflection surface 102 a is shaped to changethe curvature radius from the innermost circumferential position G₁ tothe outermost circumferential position G₂. That is, the reflectionsurface 102 a is not a shape of a spherical surface. Thereby, thereflection surface 102 a can generate the spherical aberration in thereflected light.

As described above, it is desirable that the spherical aberration beequal to or larger than 0.07 λrms, with regard to the light beam of thereflected light from the design center axis O to the innermostcircumferential position G₁.

That is, it is desirable that the spherical aberration of the reflectedlight that passes through the passage hole H provided in the secondconverging mirror 102 be equal to or larger than 0.07 λrms. The passagehole H provided in the second converging mirror 102 is a hole for thelight reception element 6. Part of the light that passes through thishole reaches the light reception element 6. Note that the hole for thelight reception element 6 is sufficient if it can allow the scatteredlight L to pass therethrough. Hence, the hole for the light receptionelement 6 can be plugged by using a material that allows the scatteredlight L to pass through, for example.

Moreover, in the above description, the aberration generated by thesecond converging mirror 102 is spherical aberration. However, it is nota limited to this. The aberration of the reflection surface 102 a may beastigmatism or coma aberration having a magnitude exhibiting the sameeffect. Moreover, the aberration of the reflection surface 102 a may beaberration obtained by combining at least two of the sphericalaberration, the astigmatism, or the coma aberration.

Note that the spherical aberration in a broad sense includes theastigmatism, the coma aberration, and the like. Hence, it is understoodthat the aberration of the reflection surface 102 a is sphericalaberration in a broad sense.

However, when the aberration of the reflection surface 102 a is thespherical aberration, the distortion of the detection signal S₁ due tothe influence of the aberration can be reduced, as compared with otheraberration. This is because the spherical aberration is the mostsymmetric to the design center axis O. That is, the distribution of thelight amount becomes symmetric on the light receiving surface of thelight reception element 6.

As described above, in the micro object detection apparatus 11, thelight beam 113 b generated at the particle R and reflected by the secondconverging mirror 102 does not return to the position of the particle R,because of the spherical aberration generated on the second convergingmirror 102.

The focal point of the light beam 113 b is dispersed in the y axisdirection, and thus it is possible to reduce blocking by the particle Ritself which conventionally occurred. This makes it possible toefficiently direct the scattered light traveling the third path to thelight receiving surface of the light reception element 6.

FIGS. 11, 12, and 13 are diagrams schematically illustrating the lightbeam on the third path in the micro object detection apparatus 11.

The spherical aberration added to the second converging mirror 102 ofthe micro object detection apparatus 11 of the first embodiment will bedescribed by using FIGS. 11, 12, and 13. For example, design matters tobe considered for adding the spherical aberration to the secondconverging mirror 102 will be described by using FIGS. 11, 12, and 13.

FIGS. 11, 12, and 13 are diagrams in which the components other than thefirst converging mirror 101 and the second converging mirror 102 areomitted, in order to simplify the explanation.

In FIGS. 11 and 12, the focal point position of an off-axis light beamis represented as a focal point position U₁, the focal point position ofa paraxial light beam is represented as a focal point position U₂, andthe distance between the focal point position U₁ and the focal pointposition U₂ is represented as a distance ds.

In general, when a mirror surface is a spherical surface, the focallength at the center portion of the mirror is longer than at theperipheral portion of the mirror. Hence, spherical aberration occurs.Such spherical aberration that occurs at the spherical-shaped mirrorsurface at an early stage is referred to as “initial sphericalaberration”. With the spherical aberration, the focal point position U₁of the off-axis light beam and the focal point position U₂ of theparaxial light beam are different in the optical axis direction.

Here, the optical axis is parallel to the y axis. The optical axis isidentical with the design center axis O of the second converging mirror102.

when additional spherical aberration is added to the initial sphericalaberration, the distance ds between the focal point position U₁ of theoff-axis light beam and the focal point position U₂ of the paraxiallight beam further changes in the direction of the optical axis. In thefollowing, the spherical aberration further added to the initialspherical aberration will be referred to as “additional sphericalaberration”. Note that, here, the initial spherical aberration isconsidered to be a very small value, and thus the “additional sphericalaberration” is equivalent to the value of spherical aberration generatedultimately.

For example, the additional spherical aberration has polarity. Thispolarity includes the following two types, when it is seen in a lightpropagation direction along the optical axis of the optical system.First, the focal point position U₁ of the off-axis light beam is fartherthan the focal point position U₂ of the paraxial light beam. Second, thefocal point position U₁ of the off-axis light beam is closer than thefocal point position U₂ of the paraxial light beam.

Here, the distance to the focal point position U₁ or the distance to thefocal point position U₂ is the distance from the position of the focalpoint of the second converging mirror 102, for example. Alternatively,the distance to the focal point position U₁ or the distance to the focalpoint position U₂ is the distance from the position of the first focalpoint of the first converging mirror 101, for example.

FIG. 11 is a diagram illustrating an example of the first case. FIG. 12is a diagram illustrating an example of the second case.

The polarity of the change of the distance ds from the initial sphericalaberration may be any one of the cases illustrated in FIGS. 11 and 12.The chance of the distance ds from the initial spherical aberration isgenerated by the additional spherical aberration of the secondconverging mirror 102 of the micro object detection apparatus 11illustrated in the first embodiment.

In the following, the size to which the additional spherical aberrationis set in designing the micro object detection apparatus 11 illustratedin the first embodiment will be described.

Here, the polarity of the additional spherical aberration illustrated inFIG. 12 will be described as an example.

FIG. 13 is a diagram of the configuration illustrated in FIG. 12 thatadditionally includes a parallel flat plate 300 inserted in the courseof the light beam 113 d as a simulation.

In general, when a parallel flat plate of a certain thickness isinserted in the course of the collected light, the focal point positionU₁ of the off-axis light beam moves in a direction in which itapproaches the focal point position U₂ of the paraxial light beam, inthe light propagation direction along the optical axis of the opticalsystem. This action corrects the additional spherical aberration, andthe parallel flat plate 300 can move the focal point position U₁ and thefocal point position U₂ to the same focal point position U₃.

For example, the numerical aperture NA of the light beam group of thelight beam 113 d is set to 0.4226 (the light flux divergence angle ofapproximately 25°); the light, wavelength is set to 660 nm; therefractive index n of the parallel flat plate 300 is set to 1.5; and thethickness of the parallel flat plate 300 is set to thickness t. Here,the “light beam group” is a light flux.

For example, the particle size of dust or pollen is assumed to be from20 μm to 100 μm. In this case, it is desirable that the additionalspherical aberration be from 6 λpv to 30 λpv. The additional sphericalaberration can be increased up to 50 λpv. That is, an effect ofdetecting the dust or the pollen can be expected by setting theadditional spherical aberration from 6 λpv to 50 λpv.

As described above, in general, the spherical aberration of the light ina collected state is smaller than 0.07 λrms. The PV value of thespherical aberration is obtained by multiplying the RMS value of theaberration by a coefficient 6√5 (≈13.41641). Thus, 0.07 λrms isapproximately 0.939 λpv. 6 λpv is approximately 6.4 times the valuecorresponding to 0.07 λrms. Moreover, 30 λpv is approximately 32 timesthe value corresponding to 0.07 λrms. Moreover, 50 λpv is approximately53.2 times the value corresponding to 0.07 λrms.

A case in which the additional spherical aberration is set to 30 λpvwill be described. The relationship between the thickness t, therefractive index n, the NA for the light flux and the sphericalaberration W40pv of the parallel flat plate 300 is expressed by thefollowing equation 1.W40pv=(t/8)×((n ²−1)/n ³)×NA ⁴)  (1)

The additional spherical aberration of the second converging mirror 102is set to 30 λpv when the parallel flat plate 300 is not used. The lightwavelength is set to 660 nm; the NA is set to 0.4226; and the refractiveindex n is set to 1.5. If the parallel flat plate 300 is added underthis condition, the thickness d of 13.4 mm is necessary for the parallelflat plate 300 in order to correct the additional spherical aberration(30 λpv) of the second converging mirror 102 to zero.

As described above, the second converging mirror 102 is designed byexpediently assuming the parallel flat plate 300 illustrated in FIG. 13,for example. The parallel flat plate 300 is a means for generating thespherical aberration.

That is, at the time of designing, the second converging mirror 102 isdesigned so as to make the distance ds to be zero when the parallel flatplate 300 is disposed. That is, the reflection surface of the secondconverging mirror 102 is formed to be an aspherical surface. Thethickness d of the parallel flat plate 300 is changed, according to thevalue of the spherical aberration to be set.

Thereby, the spherical aberration of the second converging mirror 102can be set in the above range of 6 λpv to 50 λpv. Thus, the light beam113 b generated at the particle R and reflected by the second convergingmirror 102 does not converge at the position of the particle R again.

Conversely, the magnitude of the spherical aberration of the secondconverging mirror 102 can be checked by using the parallel flat plate300. That is, by preparing several parallel flat plates 300 of differentthicknesses t, it is checked which one of the parallel flat plates 300makes the aberration small.

The blocking the scattered light by the particle R itself, whichconventionally occurred, can be reduced by dispersing the focal pointsof the light beam 113 b in the y axis direction (the optical axisdirection of the second converging mirror 102). Thereby, the scatteredlight on the third path can be directed to the light receiving surfaceof the light reception element 6 efficiently.

As described in the above example, the spherical aberration is smallerthan 0.07 λrms, in a state that light is collected. In consideration ofthis, the additional spherical aberration (6 λpv to 50 λpv) generated atthe second converging mirror 102 is not within the extent that isgenerated due to a production error occurring when the second convergingmirror 102 is simply processed to have a spherical surface. The designis made by taking proactively generating the spherical aberration intoconsideration.

In the above description, particles of dust or pollen which arecomparatively large in diameter are assumed, when the aspherical shapeof the second converging mirror 102 is designed. However, the microobject detection apparatus 11 has a purpose to detect a small particle,in some cases. The small particle has a particle diameter of 10 μm(PM10), 2.5 μm (PM2.5), or the like, for example.

In a case of detection of a small particle (for example, PM10 or PM2.5),the air actually contains pollen or dust larger than the small particle.Hence, the large particles cause erroneous detection at the time ofdetection of the small particle (for example, RM10 or PM2.5) as adetection target. However, the small particle is not limited to PM10 orPM2.5. It can be another particle, such as PM1 or PM0.5.

That is, the intensity of the scattered light from the large particle isreduced due to blocking by the large particle itself. The scatteredlight of which the light intensity is reduced is incident on the lightreception element 6. When the intensity of the scattered light from thelarge particle is approximately equal to the intensity of the scatteredlight from the small particle (PM10 or PM2.5), the light blocking of thescattered light by the large particle itself causes erroneous detection.

Thus, even in the case of the micro object detection apparatus 11 fordetecting a small particle (PM10 or PM2.5), it is necessary to considerthe shape of the aspherical surface of the second converging mirror 102,assuming that there are large particles, in order to prevent theerroneous detection. The large particle is a particle of dust or pollenhaving a diameter of 20 μm to 100 μm, or the like, for example.

In the micro object detection apparatus 11 according to the firstembodiment, which is described above, the light beam 113 b generated atthe particle R and reflected by the second converging mirror 102 doesnot converge at the position of the particle R again. Thus, lightblocking of the light beam 113 b by the particle R itself, whichconventionally occurred, can be reduced. In addition, the shielding bythe particle R itself, which conventionally occurred, can be reducedeffectively. Thereby, the scattered light (the light beam 113 a) on thethird path can be directed to the light receiving surface of the lightreception element 6 efficiently.

Moreover, the micro object detection apparatus 11 can prevent generationof a quasi peak like the maximum peak points AP₁, Ap₂ in FIG. 9. Thus,miscounting (miscounting) of the number of particles R in the peaknumber counter 63 can be reduced. Thus, the accuracy of measuring thenumber of particles R, the number of particles R per unit volume, theweight of the particles R per unit volume, and the like can be improved.

The configuration of the first embodiment can also be applied to theconfigurations of other second and third embodiments described later.

Second Embodiment

FIG. 14 is a block diagram illustrating a detection circuit unit 70 of amicro object detection apparatus 12 according to a second embodiment.

The micro object detection apparatus 12 differs from the micro objectdetection apparatus 11 according to the first embodiment only withregard to a part corresponding to the detection circuit unit 60. Thatis, the micro object detection apparatus 12 can include the detectionoptical system 50 of the micro object detection apparatus 11. Inaddition, the micro object detection apparatus 12 can include thedetection optical system 51 of the conventional micro object detectionapparatus.

Thus, detailed description will be omitted, with regard to theconfiguration of the detection optical system of the micro objectdetection apparatus 12.

With the configuration of the detection optical system 51, the microobject detection apparatus 12 exerts its effect, when the waveform F₁ ofthe detection signal S₁ for one particle R includes two maximum peakpoints Ap₁, Ap₂ and one minimum peak point Ap₃. That is, the microobject detection apparatus 12 exerts its effect when the detectionsignal S₁ is the waveform F₁ illustrated in FIG. 9 described in thefirst embodiment.

Moreover, with the configuration of the detection optical system 50, themicro object detection apparatus 12 exerts its effect, when two maximum,peaks Ap₄, Ap₅ remain in the waveform F₃ illustrated in FIG. 10. Inaddition, the micro object detection apparatus 12 exerts its effect,when the detection signal S₁ includes a quasi peak.

In the following, the configuration of the detection circuit unit 70 ofthe micro object detection apparatus 12 according to the secondembodiment will be described by using the block diagram, of FIG. 14.

The detection circuit unit 70 includes a maximum peak detector 71, aminimum peak detector 72, and a particle determination unit 80. A peakdetector 76 includes the maximum peak detector 71 and the minimum peakdetector 72. Moreover, the detection circuit unit 70 can include anamplifier circuit 61 and a peak number counter 63. The particledetermination unit 80 includes an adjacent peak determination unit 73.The particle determination unit 80 can include a peak differencedetermination unit 74 or a quasi peak elimination unit 75.

The following description will be given by using the reference signs ofFIG. 9, for example.

The amplifier circuit 61 amplifies or attenuates the level of an outputsignal S₁. The amplifier circuit 61 outputs a signal S₂.

The signal S₂ is obtained by amplifying or attenuating the level of theoutput signal S₁.

The amplifier circuit 61 can be removed when a sufficient signal levelis satisfied in the subsequent processing, for example.

The peak detector 76 receives the signal S₂. The maximum peak detector71 detects the maximum peak points Ap₁, Ap₂ of the output signal S₂ ofthe amplifier circuit 61. The maximum peak detector 71 sequentiallyprocesses the detection of the maximum peak points Ap₁, Ap₂ of theoutput signal S₂. The minimum peak detector 72 detects the minimum peakpoint Ap₃ of the output signal S₂ of the amplifier circuit 61. Theminimum peak detector 72 sequentially processes the detection of theminimum peak point Ap₃ of the output signal S₂. The peak detector 76outputs a signal S₄.

The particle determination unit 80 receives the signal S₄. The signal S₄includes information on the maximum peak points Ap₁, Ap₂ output by themaximum peak detector 71 and information on the minimum peak point Ap₃output by the minimum peak detector 72. The particle determination unit80 determines whether or not the maximum peaks are maximum peaksgenerated in a quasi manner.

The particle determination unit 80 includes the adjacent peakdetermination unit 73. The particle determination unit 80 can includethe peak difference determination unit 74 or the quasi peak eliminationunit 75.

The adjacent peak determination unit 73 receives the signal S₄. Theadjacent peak determination unit 73 determines whether or not each ofthe peak value P₁ and the peak value P₂ is a value of a maximum peakpoint Ap that is adjacent temporally. The detection results (signal S₄)of the maximum peak detector 71 and the minimum peak detector 72 areused in the determination of the adjacent peak determination unit 73.That is, the peak values P₁, P₂ detected by the maximum peak detector 71and the peak value P₃ detected by the minimum peak detector 72 are usedin the determination for the adjacent peak determination unit 73.

The adjacent peak determination unit 73 determines whether or not thepeak value P₁ and the peak value P₂ are the quasi peaks of the maximumpeak point Ap.

The adjacent peak determination unit 73 determines whether or not themaximum peak value P₁, the maximum peak value P₂, and the minimum peakvalue P₃ are detected in the order of the maximum peak value P₁, theminimum peak value P₃, and the maximum peak value P₂. The adjacent peakdetermination unit 73 sends the determination result (signal S₅) ofwhether or not the peak values P₁, P₂, P₃ are in this order (P₁→P₃→P₂),to the peak difference determination unit 74 of the subsequent stage.The adjacent peak determination unit 73 outputs the signal S₅.

The adjacent peak determination unit 73 determines whether or not theminimum peak value P₃ is between the maximum peak value P₁ and themaximum peak value P₂.

The peak difference determination unit 74 receives the signal S₅. Thepeak difference determination unit 74 determines the magnituderelationship between the absolute difference value ΔP₁ and a setdifference value on the basis of the result of the determination (signalS₅) by the adjacent peak determination unit 73.

The peak difference determination unit 74 determines whether or not theabsolute difference value ΔP₁ between the peak value P₁ and the peakvalue P₃ is larger than a preset set difference value ΔP₃, for example.The absolute difference value ΔP₁ is the absolute value of the valueobtained by subtracting the peak value P₃ from the average value of thepeak value P₁ and the peak value P₂, for example.

When the absolute difference value ΔP₁ is larger than the presetdifference value ΔP₀, the peak difference determination unit 74determines that a particle R existed at each of the maximum peak pointAp₁ and the maximum peak point Ap₂. The value of the maximum peak pointAp₁ is the maximum peak value P. The value of the maximum peak point Ap₂is the maximum peak value P₂. Thus, the peak number counter 63 adds “2”to the count number, assuming that two particles R existed.

On the other hand, when the absolute difference value ΔP₁ is smallerthan the preset difference value ΔP₀, the peak difference determinationunit 74 determines that a quasi maximum peak was generated in thedetection signal SA. The quasi maximum peak is generated by theshielding effect of the particle R itself. The peak differencedetermination unit 74 determines that one particle R existed, from thecombination of the maximum peak point Ap₁ and the maximum peak pointAp₂. Thus, the peak number counter 63 adds “1” to the count number,assuming that one particle R existed.

Note that the quasi maximum, peak has the same meaning as the abovequasi peak.

Moreover, the peak difference determination unit 74 can determine themaximum peak values P₁, P₂ and the minimum peak value P₃, by using avalue other than the absolute difference value ΔP₁. For example, thepeak difference determination unit 74 can determine the maximum peakvalues P₁, P₂ and the minimum peak value P₃ by using a ratio of themaximum peak values P₁, P₂ and the minimum peak value P. That is, thepeak difference determination unit 74 can use the difference, the ratio,or the like between the maximum peak values P₁, P₂ and the minimum peakvalue P₃.

The peak difference determination unit 74 outputs a signal S₆.

The quasi peak elimination unit 75 receives the signal S₆. The quasipeak elimination unit 75 determines whether or not to eliminate thequasi maximum peak, on the basis of the determination result (signal S₆)by the peak difference determination unit 74. The quasi maximum peak isa peak of the detection signal S₁ generated by the shielding effect ofthe particle R itself.

The quasi peak elimination unit 75 outputs a signal S₇.

The peak number counter 63 counts the number of peaks corresponding tothe detection of the particle R, on the basis of the determinationresult (signal S₇) of the particle determination unit 80.

The number concentration or the weight concentration of the particles Rcan be calculated by using the count value of the number of peaksobtained by the peak number counter 63 of the detection circuit 60 orthe detection circuit 70.

The micro object detection apparatuses 11, 12 calculate the numberconcentration or the weight concentration of the particles R, by usingthe count value of the number of peaks.

For example, the number concentration of the particles R is calculatedby dividing the count value during a predetermined certain amount oftime, by a gas volume, a liquid volume, or the like.

According to the micro object detection apparatus 12 of the secondembodiment, which has been described above, the error in counting(miscounting) the number of particles R in the detection circuit unit 70due to the generation of the quasi peak can be reduced in addition, themeasurement accuracy of the number concentration, the weightconcentration, or the like can be improved.

Third Embodiment

FIG. 15 is a configuration diagram schematically illustrating aconfiguration of a detection optical system 52 of the micro objectdetection apparatus 11 according to a third embodiment.

The detection optical system 52 of the micro object detection apparatus11 according to the third embodiment includes another detection opticalsystem (second detection optical system 52 b), in the conventionaldetection optical system 51 illustrated in FIG. 8, the detection opticalsystem 50 of the first embodiment, and the detection optical system 50of the second embodiment. In the following, the detection opticalsystems 50, 51 are referred to as a first detection optical system. Inthe third embodiment, the part corresponding to the detection opticalsystems 50, 51 is referred to as a first detection optical system 52 a.

The second detection optical system 52 b mainly receives the scatteredlight (a light beam 114 on a fourth path) that directly passes throughan opening AP, among the scattered light emitted from the particle R.Then, the second detection optical system 52 b detects the opticalproperty of the particle R, on the basis of the light beam 114. Theopening AP is provided in the first converging mirror 103.

For example, the second detection optical system 52 b detects the sizeor the shape of the particle R, for example. In addition, the seconddetection optical system 52 b identifies the type of the particle R fromthe fluorescence property or the like of the particle R, for example.That is, the second detection optical system 52 b is a detection opticalsystem that can classify the features of the particles R.

With the second detection optical system 52 b, the micro objectdetection apparatus 11 can determine a larger number of types ofparticles R than in the past. Moreover, the micro object detectionapparatus 11 can determine the particle R more accurately than in thepast.

In the third embodiment, the second detection optical system 52 b candetect the property of the particle R or the like, without impairing theefficiency of the scattered light of the light beam 113 d. The scatteredlight of the light beam 113 d is the scattered light directed to thelight reception element 6 via the first converging mirror 103 and thesecond converging mirror 104.

In the following, the second detection optical system 52 b detectspolarized light components of the scattered light of the particle R, forexample. The second detection optical system 52 b determines the type ofthe particle R on the basis of the information indicating the shape ofthe particle R which is obtained from the polarized light components ofthe scattered light. The second detection optical system 52 b determinesthe particle of the pollen and the particle of the dust (dust), forexample. The particle of the pollen has a shape close to a sphericalshape. On the other hand, the particle of the dust has an asphericalshape.

FIGS. 15 and 16 are configuration diagrams schematically illustratingthe configuration of the optical system 52 of the micro object detectionapparatus 11 according to the third embodiment, for example.

FIG. 15 is a configuration diagram illustrating a cross section in thex-y plane of the detection optical system 52 of the micro objectdetection apparatus 11. In FIG. 15, the second detection optical system52 b includes a lens 160, light reception elements 161, 162, and apolarization prism 163. However, a member that holds these components isomitted.

FIG. 16 is a configuration diagram illustrating a cross section in thez-x plane of the optical system 520 of the micro object detectionapparatus 11. However, to make the description easy, the lens 160, thepolarization prism 163, the light reception element 161, and the lightreception element 162 of the second detection optical system 52 b areomitted in FIG. 16.

The detection optical system 52 includes the second detection opticalsystem 52 b in addition to the detection optical system 50.

In the detection optical system 52, the second detection optical system52 b is provided on the first converging mirror 103 side. The firstconverging mirror 103 faces the second converging mirror 104.

The opening AP is an opening to take the scattered light (the light beam114) from the particle R into the second detection optical system 52 b.The opening AP is provided in the first converging mirror 103.

The opening AP is located on the center axis O of the first convergingmirror 103, for example. In FIGS. 15 and 16, the center of the openingAP is located on the center axis O.

As illustrated in FIG. 16, the opening AP has a circle shape. The radiusof the opening AP is radius r₁. However, the shape is not limited tothis, but may be other than the circle.

The scattered light 113 b reflected by the second converging mirror 104is directed to the light reception element 6 via the first convergingmirror 103. In the third embodiment, the opening AP is formed in thefirst converging mirror 103, such that the scattered light 113 b doesnot reach the opening AP, for example. The opening AP is positionedinside the region surrounded by the points at which the scattered light113 b reflected by the periphery of the passage hole H reaches the firstconverging mirror 103. That is, the opening AP is located inside theshape of the periphery of the passage hole H projected on the firstconverging mirror 103 by the scattered light 113 b.

Moreover, the opening AP can include the region surrounded by the pointsat which the scattered light 113 b reflected by the periphery of thepassage hole H reaches the first converging mirror 103. That is, theopening AP can include the region surrounded by the shape of theperiphery of the passage hole H projected on the first converging mirror103 by the scattered light 113 b.

A hole DL is a hole for installing the lens 160, for example.

The hole DL is provided in the first converging mirror 103.

The hole DT, located on the same axis as the opening AP, for example.The end portion of the −y axis side of the hole DL is connected to theend portion of the +y axis side of the opening AP. For example, thediameter of the hole DT, is larger than the diameter of the opening AP.

The lens 160 is inserted in the hole DL, from the +y axis side of thehole DL. The diameter of the lens 160 is larger than the diameter of thehole DL. The position of the lens 160 in the y axis direction inrelation to the first converging mirror 103 is decided at the endportion of the H-v axis side of the opening AP. The position of the lens160 on the plane is decided by the hole DL.

The lens 160 allows the scattered light (the light beam 114) from theparticle R to directly enter thereinto. The lens 160 converges theincident scattered light (the light beam 114), for example. The lens 160forms light spots on the light reception elements 161, 162.

The lens 160 is an example of a light converging element for convergingthe scattered light (the light beam 114) from the particle R. Note thatthe lens 160 is not needed necessarily.

The polarization prism 163 is located on the +y axis side of the lens160.

The polarization prism 163 is an example of a polarized light separatingelement.

The scattered light (the light beam, 114) coming from the lens 160 isseparated by the polarization prism 163. The light coming from the lens160 is separated by the polarization prism 163, on the basis of thelight polarization direction of the light. For example, the P-polarizedlight (a light beam 114 p) travels to the light reception element 161from the polarization prism 163. The S-polarized light (a light beam 114s) travels to the light reception element 162 from the polarizationprism 163.

The oscillation of the P-polarized light (the light beam 114 p) isorthogonal to the oscillation of the S-polarized light (the light beam,114 s). That is, the P-polarized light (the light beam 114 p) oscillatesorthogonally to the oscillation of the S-polarized light (the light beam114 s).

The light reception elements 161, 162 are located to face thepolarization prism 163. For example, the light reception element 161 islocated to face a P-polarized light (light beam 114 p) projectionsurface 163 p of the polarization prism 163. For example, the lightreception element 162 is located to face an S-polarized light (lightbeam 114 s) projection surface 163 s of the polarization prism 163.

The scattered light detected by the light reception element 161 is theP-polarized light (the light beam 114 p) that has transmitted throughthe polarization prism 163. On the other hand, the scattered lightdetected by the light reception element 162 is the S-polarized light(the light beam 114 s) reflected by a reflection surface 164 of thepolarization prism 163. The S-polarized light component is the componentin the orthogonal direction to the P-polarized light component.

Here, the intensity of the light detected by the light reception element161 is and the intensity of the light detected by the light receptionelement 162 is Is.

For example, the shape of the particle R can be detected, using thepolarization degree expressed by the following equation 2 as an index.The “shape of the particle R” is the degree of flatness with referenceto a true spherical shape, for example. This degree of flatness isreferred to as “sphericity degree”.Polarization degree (sphericity degree)=(Ip−Is)/(Ip+Is)  (2)

The type of the particle R can be identified by computation usingequation 2. However, the computation equation for calculating thesphericity degree is not limited to this. The computation equation maybe another computation equation whose value changes according to theshape of the particle R similarly.

As described above, the micro object detection apparatus 11 includes thefirst detection optical system 52 a and the second detection opticalsystem 52 b. The first detection optical system 52 a collects thescattered light by using the converging mirrors 103, 104, and detects afine particle. On the other hand, the second detection optical system 52b allows the scattered light (the light beam 114) to directly enterthereinto, and detects a fine particle.

Providing a polarized light optical system as the second detectionoptical system 52 b is effective, when there is a need for a polarizedlight optical system for detecting the P-polarized light and theS-polarized light included in the scattered light, as described above.This is because, when the scattered light from the particle R isreflected, for example, by the first converging mirror 103, the secondconverging mirror 104, or the like, the ratio of the P-polarized lightand the S-polarized light changes. Thus, an error is caused indetermination of the shape (the sphericity degree) of the particle R byusing the polarization degree as an index, and the accuracy ofidentification of the type of the particle R decreases.

Moreover, when the first detection optical system 52 a detects thescattered light by using the first converging mirror 103 and the secondconverging mirror 104, a direction of the detection by the firstdetection optical system 52 a covers a wide range. That is, the firstdetection optical system 52 a receives the lateral scattered light Ls,the forward scattered light Lfs, and the backward scattered light Lbs.The detection by the first detection optical system 52 a receives thelateral scattered light Ls of a wide range, for example.

However, detecting the direct scattered light from the particle H iseffective, when the feature of the particle R can be detected bydetecting only one of the lateral scattered light Is, the forwardscattered light Lfs, and the backward scattered light Lbs. In this case,the light received by the light reception element can be limited to thescattered light in a certain direction. In the case of such a detectiontarget, using the second detection optical system 52 b is effective.

Positions DI, DO illustrated in FIG. 16 are the positions of thescattered light (the light beam 113 c) that is reflected by the secondconverging mirror 104 and reaches the first converging mirror 103. Thepositions DI indicate the positions of the closest side to the centeraxis O. The positions DO indicate the positions of the farthest sidefrom the center axis O. In FIG. 16, the positions DI are represented byan alternate long and short dash line. The positions DO are representedby an alternate long and short dash line.

Here, each of the positions DI and the positions DO is a circle, to makethe description easy. The radius of the positions DI is a radius RI. Theradius of the positions DO is a radius RO.

That is, the light beam 113 c of the scattered light reaches between thepositions DI and the positions DO on the first converging mirror 103.

The passage hole H for taking the scattered light is provided on thesecond converging mirror 104 side, in the micro object detectionapparatus 11 that detects the scattered light by the two oppositeconverging mirrors 103, 104. The scattered light accepted through thispassage hole H is received by the light reception element 6.

In the case of such an optical system, there is a region that the lightbeam 113 c reflected by the second converging mirror 104 does not reach,near the center axis O on the first converging mirror 103. The regionthat the light beam 113 c does not reach is the inside of the positionsDI.

The opening AP is provided in the region on this first converging mirror103 which the light beam 113 c does not reach.

Thereby, the scattered light (the light beam 114) that directly reachesfrom the particle R can be accepted through the opening AP. In addition,the efficiency of the scattered light (the light beam 113 c) directed tothe light reception element 6 via the first converging mirror 103 andthe second converging mirror 104 is not impaired. The first detectionoptical system 52 a can efficiently direct the light beam 113 c of thescattered light to the light reception element 6.

Here, the center of the opening AP may be offset from the center axis O,within a range having a small influence on the reflection efficiency ofthe scattered light on the first converging mirror 103. Moreover, theradius r₁ of the opening AP may be large to allow the light beam 113 cof the scattered light to enter into the opening AP.

Moreover, when influence on the accuracy of detection in the seconddetection optical system 52 b is small, the center of the opening AP maybe moved from the center axis O. That is, the opening AP can be locatedon the reflection surface of the first converging mirror 103.

In FIG. 16, the radius r₁ is set smaller than the radius RI. If theopening AP is set to satisfy this condition, the efficiency of thescattered light directed to the light reception element 6 via the firstconverging mirror 103 and the second converging mirror 104 is notimpaired. Thus, the first detection optical system 52 a can efficientlydirect the light beam 113 c of the scattered light to the lightreception element 6.

The detection optical system 52 of FIGS. 15 and 16 includes the lens160. However, when the detection efficiency of the scattered light issufficient, the lens 160 can be removed as necessary. In that case, thehole DL provided in the first converging mirror 103 is unnecessary. Thatis, the penetrating opening AP is provided in the first convergingmirror 103.

Moreover, the first converging mirror 103 can have a function of thelens 160, as another form of the micro object detection apparatus 11according to the third embodiment. That is, in the third embodiment, thelens 160 is integrated with the first converging mirror 103. A region.(a lens portion 165) provided on the first converging mirror 103 andhaving a lens function allows the light to transmit toward a seconddetection optical system 53 b side.

FIG. 17 is a configuration diagram schematically illustrating aconfiguration of a detection optical system 53 of another form of themicro object detection apparatus 11 according to the third embodiment ofthe present invention.

The detection optical system 53 includes a first detection opticalsystem 53 a and a second detection optical system 53 b.

A lens portion 165 is provided in the first converging mirror 103. Thelens portion 165 is located on the center axis O of the first convergingmirror 103, for example.

The lens portion 165 can direct the scattered light (the light beam 114)from the particle R to the second detection optical system 53 b. In FIG.17, the radius of the lens portion 165 is a radius r₃. In FIG. 17, thelens portion 165 converges the incident scattered light. The scatteredlight converged by the lens portion 165 is incident on the polarizationprism 163.

FIG. 18 is a block diagram illustrating a detection circuit unit 65 of amicro object detection apparatus 13 that includes the detection opticalsystem, 53. Note that the micro object detection apparatus 13illustrated in FIG. 18 can include the detection optical system 52.

The detection circuit unit 65 includes maximum, peak detectors 62 a, 62b, 62 c, a peak number counter 63, and a particle type determinationunit 64. The detection circuit unit 65 can include amplifier circuits 61a, 61 b, 61 c or a maximum peak detector 62 a.

The light reception elements 6, 161, 162 output signals S₁₂, S₁₃,similarly to the detection circuit unit 60 of FIG. 7.

The amplifier circuits 61 a, 61 b, 61 c receive the signals S₁₁, S₁₂,S₁₃. The amplifier circuits 61 a, 61 b, 61 c amplify or attenuate thesignals S₁₁, S₁₂, S₁₃. The amplifier circuits 61 a, 61 b, 61 c outputsignals S₂₁, S₂₂, S₂₃. The amplifier circuits 61 a, 61 b, 61 c can beremoved, if the sufficient signal level is satisfied in the subsequentprocessing, for example.

The maximum peak detectors 62 a, 62 b, 62 c receive the signals S₂₁,S₂₂, S₂₃. The maximum peak detectors 62 a, 62 b, 62 c detect the maximumpeak points of the output signals S₂₁, S₂₂, S₂₃ of the amplifiercircuits 61 a, 61 b, 61 c. The maximum peak points of the output signalsS₂₁, S₂₂, S₂₃ correspond to the particle R. The maximum peak detectors62 a, 62 b, 62 c sequentially process the detection of the maximum peakpoints of the output signals S₂₁, S₂₂, S₂₃. Note that the maximum peakdetector 62 a can be removed, if the number of particles P can becounted by using a threshold value or the like, without detecting themaximum peak point, for example.

The peak number counter 63 receives signals S₃₁, S₃₂, S₃₃ indicating themaximum peak points, which are output by the maximum peak detectors 62a, 62 b, 62 c. The peak number counter 63 counts the number of peakscorresponding to the detection of the particle R. The peak numbercounter 63 is a counter that counts the number of peaks of the signalsS₃₁, S₃₂, S₃₃.

The particle type determination unit 64 receives the signals S₃₁, S₃₂,S₃₃ indicating the maximum peak points, which are output by the maximumpeak detectors 62 a, 62 b, 62 c. The particle type determination unit 64determines the type of the particle R, on the basis of the signals S₃₁,S₃₂, S₃₃. The particle type determination unit 64 is a determinationunit that determines the type of the particle R on the basis of thesignals S₃₁, S₃₂, S₃₃.

For example, when detecting that the value of the signal S₃₂ is the sameas the value of the signal S₃₃, the particle type determination unit 64determines that the particle R is pollen. For example, when determiningthat the value of the signal S₃₂ is the same as the value of the signalS₃₃, the particle type determination unit 64 determines that theparticle R is pollen. Moreover, when detecting that the value of thesignal S₃₂ is different from the value of the signal S₃₃, the particletype determination unit 64 determines that the particle R is dust, forexample. For example, when determining that the value of the signal S₃₂is different from the value of the signal S₃₃, the particle typedetermination unit 64 determines that the particle R is dust. The signalS₃₂ indicates the maximum peak value of the output signal S₁₂ of thelight reception element 161. The signal S₃₃ indicates the maximum peakvalue of the output signal S₁₃ of the light reception element 162.

For example, when detecting the signal S₃₁ and not detecting the signalS₃₂ and the signal S₃₃, the particle type determination unit 64determines that the particle R is PM2.5 or PM10. The signal S₃₁indicates the maximum peak value of the output signal S₁₁ of the lightreception element 6. The light reception elements 161, 162 mainlyreceive the scattered light that enters directly. Hence, when theparticle R is PM2.5 or the like, the values of the signal S₁₂, S₁₃ aresmall.

The particle type determination unit 64 is also employed in the microobject detection apparatuses 11, 12 that include the detection opticalsystems 50, 51. The micro object detection apparatuses 11, 12 determinethe type of the particle R by the particle type determination unit 64,on the basis of the light intensity of the scattered light.

The micro object detection apparatus 11 according to the thirdembodiment includes the first detection optical system 52 a and thesecond detection optical system 52 b.

The first detection optical system 52 a detects a particle whose lightamount of the scattered light is comparatively small, by the lightreception element 6. The particle whose light amount of the scatteredlight is comparatively small is PM2.5 or the like, for example.

On the other hand, the second detection optical system 52 b detects aparticle whose light amount of the scattered light is comparativelylarge, by the light reception elements 161, 162. The particle whoselight amount of the scattered light is comparatively large is a particlehaving a larger particle size than PM2.5. The particle whose lightamount of the scattered light is comparatively large is a particle suchas pollen or dust, for example.

Howe these are an example for describing the micro object detectionapparatus 11. The type of the particle R of the detection target in thefirst detection optical system 52 a and the second detection opticalsystem 52 b is not limited thereto.

If the fluorescence of the detection target particle R is detected, thefirst detection optical system 52 a may be a detection optical systemfor detecting the fluorescence, for example. The light reception element6 detects whether or not the detection target particle R has thefluorescence.

Moreover, the second detection optical system 52 b can be a detectionoptical system that receives the scattered light from the particle R anddetects the particle size or shape.

The irradiation light to the particle R acts as excitation light, toemit the fluorescence. The fluorescence has a wavelength λf that differsfrom the wavelength λf of the irradiation light. In general, thewavelength λf of the fluorescence is longer than the wavelength λe ofthe excitation light, in many cases. That is, it is the relationship ofwavelength λf>wavelength λe.

In general, the fluorescence is weak. In addition, the first detectionoptical system 52 a can collect a larger amount of scattered light.Hence, the first detection optical system 52 a is suitable for detectionof the fluorescence.

In order to determine whether or not the particle R is a fluorescentsubstance that emits the fluorescence, the fluorescence included in thescattered light from the particle R is divided and directed to the lightreception element 6. The dividing method can be an optical filterprovided in the prior stage of the light reception element 6, forexample. The optical filter is a dichroic filter or the like, forexample. The optical filter allows the light of the fluorescencewavelength λf to transmit. The optical filter blocks the light of thewavelength λe of the irradiation light. Whether or not the particle R isthe fluorescent substance can be determined, in accordance with thelight amount of the fluorescence, on the basis of the detection wavyform output from the light reception element 6.

When the particle R is the fluorescent substance, the fluorescence isdetected by the first detection optical system 52 a. In addition, thescattered light is detected by the second detection optical system 52 b.The scattered light detected by the second detection optical system 52 bhas the same wavelength as the wavelength λe of the irradiation light,for example. Thereby, the particle R can be determined to be thefluorescent substance.

On the other hand, when the particle R is not the fluorescent substance,the fluorescence is not detected by the first detection optical system52 a. The scattered light is detected by the second detection opticalsystem 52 b. The scattered light detected by the second detectionoptical system 52 b has the same wavelength as the wavelength λe of theirradiation light, for example. Thereby, the particle R can bedetermined to not be the fluorescent substance.

As described above, the first detection optical system 52 a and thesecond detection optical system 52 b can select the detection method,according to the detection target particle R. The detection method isthe light amount of the scattered light, the polarized light of thescattered light, the wavelength of the scattered light, or the like, forexample.

As described above, in the detection optical system 52, the seconddetection optical system 52 b is provided on the first converging mirror103 side. Thereby, the reflection angle of the scattered light on thesecond converging mirror 104 can be node small. Thus, the decrease inthe accuracy in detecting the polarized light components of thescattered light can be prevented.

Moreover, as described above, the opening AP is provided in the regionon the first converging mirror 103 that the light beam 113 c does notreach. The opening AP is positioned on the first converging mirror 103that the scattered light reaches when the scattered light is reflectedby the passage hole H. The opening AP includes a region surrounded bythe points at which the scattered light reflected by the periphery ofthe passage hole H reaches the first converging mirror 103.Alternatively, the opening AP is positioned inside the region surroundedby the points at which the scattered light reflected by the periphery ofthe passage hole H reaches the first converging mirror 103. The openingAP is located at the position opposite to the passage hole H. The seconddetection optical system 52 b that receives the scattered light thatdirectly enters without being reflected by the second converging mirror104 is provided at the position opposite to the passage hole H.

Thereby, the second detection optical system 52 b can reduce thereceived light amount of the scattered light reflected by the secondconverging mirror 104. Thus, the decrease in the accuracy in detectingthe polarized light components of the scattered light can be prevented.

The passage hole H and the opening AP are examples of the passageregion. The passage region is a region that, allows the light to passtherethrough. The passage region is a hole for example, and the passageregion is a region or the like in which a transparent member is locatedfor example.

The scattered light can reach the light reception element 6 by passingthrough the passage hole H, for example. The second converging mirror104 includes the passage region (the passage hole H) that allows thescattered light directed to the light reception element 6 to passtherethrough. The scattered light can reach the second detection opticalsystems 52 b, 53 b by passing through the opening AP, for example. Thefirst converging mirror 103 includes the passage region (the opening AP)that allows the scattered light, directed to the second detectionoptical systems 52 b, 53 b to pass therethrough.

Moreover, the light reception element 6 can be located at the positionof the passage hole H, for example. Moreover, the second detectionoptical systems 52 b, 53 b can be located at the position of the openingAP, for example.

As above, the detection optical systems 52, 53 of the micro objectdetection apparatus 11 according to the third embodiment can detectmicro particulate matter such as PM2.5, pollen and the like, by oneoptical system.

Note that, when terms indicating positional relationships betweencomponents such as “parallel”, “perpendicular”, and “center” or termsindicating the shapes of components, are used in each of the aboveembodiments, these terms include a range considering manufacturingtolerance, variation in assembly, and the like. Hence, even when“substantially” is not recited in the claims, the range consideringmanufacturing tolerance, variation in assembly, and the like isincluded.

Although the embodiments of the present invention have been described asabove, the present invention is not limited to these embodiments.

On the basis of the above embodiments, the detail of the invention willbe recited as additional statement (1) to additional statement (4) inthe following. In each of additional statement (1) to additionalstatement (4), reference numbers are given independently. Thus, forexample, “additional statement 1” exists in both of additional statement(1) and additional statement (2).

Note that the feature of the device of additional statement (1) can beincorporated in the device of additional statement (2) to additionalstatement (4). Moreover, the feature of the device of additionalstatement (2) can be incorporated in the device of additional statement(3) or additional statement (4). Moreover, the feature of the device ofadditional statement (3) can be incorporated in the device of additionalstatement (4). Moreover, the device of additional statement (1),additional statement (2), or additional statement (3) can employ themethod of additional statement (3). Moreover, the feature of the deviceof additional statement (1), the feature of the device of additionalstatement (2), the feature of the device of additional statement (3),and the feature of the device of additional statement (4) can becombined. In addition, the device obtained by combining those featurescan employ the method of additional statement (3).

<Additional Statement (1)>

<Additional Statement 1>.

A micro object detection apparatus comprising:

a light radiation unit that radiates irradiation light on a particle ingas or liquid;

a first optical system that receives scattered light scattered byhitting the irradiation light against the particle, and detects anintensity of the scattered light; and

a counter that counts the number of particles, on the basis of theintensity of the scattered light detected by the first optical system,

wherein the first optical system includes a converging mirror and alight reception element,

the converging mirror includes a first reflection region and a secondreflection region, and directs the scattered light to the lightreception element,

the light reception element receives the scattered light and detects theintensity of the scattered light,

the first reflection region has an elliptical mirror shape, and reflectsthe scattered light incident directly from the particle to direct thescattered light to the light reception element, by utilizing two focalpoint positions of an ellipse,

the second reflection region reflects the scattered light incidentdirectly from the particle to direct the scattered light to the firstreflection region, so that the scattered light is reflected by the firstregion and is directed to the light reception element, and

the second reflection region has an aspherical shape to give aberrationto the scattered light reflected by the second reflection region, at afocal point position of the second reflection region.

<Additional Statement 2>

The micro object detection apparatus according to additional statement1, wherein the aberration is larger than aberration generated by aspherical mirror that approximates the aspherical shape of the secondreflection region.

<Additional Statement 3>

The micro object detection apparatus according to additional statement 1or 2, wherein the aberration generated by the second reflection regionis spherical aberration.

<Additional Statement 4>

The micro object detection apparatus according to additional statement3, whereon the spherical aberration generated by the second reflectionregion is equal to or larger than 0.07 λrms.

<Additional Statement 5>

The micro object detection apparatus according to any one of additionalstatements 1 to 4, wherein

the second reflection region includes a hole that allows the scatteredlight directed to the light reception element to pass therethrough,

a second optical system that receives the scattered light incidentdirectly without being reflected by the first reflection region isprovided at a position opposite to the hole, and

the intensity of the scattered light is detected.

<Additional Statement 6>

The micro object detection apparatus according to additional statement5, wherein the second optical system separates the scattered lightaccepted by the second optical system into polarized light components,and detects the intensity of the separated scattered light.

<Additional Statement 1>

The micro object detection apparatus according to additional statement 5or 6, wherein the counter counts the number of particles, on the basisof the intensity of the scattered light detected by the second opticalsystem.

<Additional Statement 8>

The micro object detection apparatus according to any one of additionalstatements 1 to 7, comprising a particle type determination unit thatdetermines a type of the particle on the basis of the intensity of thescattered light detected by the first optical system or the secondoptical system.

<Additional Statement (2)>

<Additional Statement 1>

A micro object detection apparatus comprising:

a first optical system including a first reflection region, a secondreflection region, and a light reception element,

wherein the first reflection region has an ellipsoidal shape, andreflects scattered light scattered when irradiation light hits aparticle, to direct the scattered light to the light reception element,by utilizing two focal point positions of the ellipsoidal shape,

the second reflection region reflects scattered light coming from theparticle to direct the scattered light to the first reflection region,so that the scattered light is directed to the light reception elementby utilizing the ellipsoidal shape of the first reflection region, and

a light flux diameter of the scattered light reflected by the secondreflection region is larger than the particle, at a position of theparticle at which the scattered light is generated.

<Additional Statement 2>

The micro object detection apparatus according to additional statement1, wherein the first reflection region is an elliptical mirror.

<Additional Statement 3>

The micro object detection apparatus according to additional statement 1or 2, wherein the second reflection region generates a plurality offocal points that differ according to positions at which reflection oflight occurs, to disperse the plurality of focal points.

<Additional Statement 4>

The micro object detection apparatus according to any one of additionalstatements 1 to 3, wherein

the second reflection region has an aspherical shape based on aspherical shape, and

the light flux diameter of the scattered light reflected by the secondreflection region is larger than the light flux diameter of thescattered light of a case where the scattered light is reflected by areflection region having the spherical shape as a basis for theaspherical shape, at the position of the particle at which the scatteredlight is generated.

<Additional Statement 5>

The micro object detection apparatus according to additional statement4, wherein the second reflection region is an aspherical mirror.

<Additional Statement 6>

The micro object detection apparatus according to additional statement 4or 5, wherein the second reflection region has the aspherical shape togive aberration to the scattered light reflected by the secondreflection region, at the focal point position of the second reflectionregion.

<Additional Statement 7>

The micro object detection apparatus according to additional statement6, wherein the aberration is larger than aberration generated by aspherical mirror that approximates the aspherical shape of the secondreflection region.

<Additional Statement 8>

The micro object detection apparatus according to additional statement 6or 7, wherein the aberration is spherical aberration.

<Additional Statement 9>

The micro object detection apparatus according to additional statement8, wherein the spherical aberration is equal to or larger than 0.07λrms.

<Additional Statement 10>

The micro object detection apparatus according to additional statement8, wherein the spherical aberration is equal to or larger than 6 λpv.

<Additional Statement 11>

The micro object detection apparatus according to any one of additionalstatements 8 to 10, wherein the spherical aberration is equal to orsmaller than 30 λpv.

<Additional Statement 12>

The micro object detection apparatus according to any one of additionalstatements 8 to 10, wherein the spherical aberration is equal to orsmaller than 50 λpv.

<Additional Statement 13>

The micro object detection apparatus according to any one of additionalstatements 1 to 12, comprising: a light radiation unit that radiates theirradiation light on the particle.

<Additional Statement (3)>

<Additional Statement 1>

A micro object detection method for detecting a peak of an input signalcorresponding to each particle in gas or liquid, to detect the number ofparticles, comprising:

determining that two local maximum values axe quasi peaks correspondingto one particle, when a local minimum value exists between the two localmaximum values of the input signal.

<Additional Statement 2>

The micro object detection method according to additional statement 1,comprising:

detecting a maximum peak of the input signal corresponding to theparticle;

detecting a minimum peak of the input signal;

detecting positions of a first maximum peak, a second maximum peak, andthe minimum peak, wherein the first maximum peak and the second maximumpeak are two maximum peaks in the input signal; and

determining whether or not the maximum peaks are the quasi peakscorresponding to the one particle on the basis of the positions of themaximum peaks and the minimum peak.

<Additional Statement 3>

The micro object detection method according to additional statement 2,comprising: detecting whether or not the minimum peak exists between thefirst maximum peak and the second maximum peak.

<Additional Statement 4>

The micro object detection method according to additional statement 2,comprising: detecting whether or not the first maximum peak, the minimumpeak, and the second maximum peak are detected in this order.

<Additional Statement 5>

The micro object detection method according to any one of additionalstatements 2 to 4, comprising: determining whether or not the firstmaximum peak and the second maximum peak are quasi peaks correspondingto one particle.

<Additional Statement 6>

The micro object detection method according to additional statement 5,comprising: determining whether or not the first maximum peak and thesecond maximum peak are the quasi peaks, on the basis of comparisonbetween the first maximum peak and the minimum peak or comparisonbetween the second maximum peak and the minimum peak.

<Additional Statement 7>

The micro object detection method according to additional statement 5,comprising: determining whether or not the first maximum peak and thesecond maximum peak are the quasi peaks, on the basis of comparisonbetween a value calculated on the basis of the first maximum peak andthe second maximum peak and the minimum peak.

<Additional Statement 8>

The micro object detection method according to additional statement 6 or7, wherein the comparison is a difference between two values.

<Additional Statement 9>

The micro object detection method according to additional statement 6 or7, wherein the comparison is a rate between two values.

<Additional Statement 10>

The micro object detection method according to any one of additionalstatements 1 to 9, comprising: determining that there is one particle,when determining that the local maximum values are the quasi peaks, anddetermining that there are two particles, when determining that thelocal maximum values are not the quasi peaks.

<Additional Statement 11>

The micro object detection method according to any one of additionalstatements 1 to 10, comprising: counting the number of particles.

<Additional Statement 12>

The micro object detection method according to any one of additionalstatements 1 to 11, comprising: calculating a number concentration or aweight concentration of the particles, on the basis of the number ofparticles.

<Additional Statement 13>

A micro object detection apparatus for detecting a peak of an inputsignal corresponding to each particle in gas or liquid, to detect thenumber of particles, wherein

the micro object detection apparatus determines that two local maximumvalues are quasi peaks corresponding to one particle, when a localminimum value exists between the two local maximum values of the inputsignal.

<Additional Statement 14>

The micro object detection apparatus according to additional statement13, comprising:

a maximum peak detector that detects a maximum peak of the input signalcorresponding to the particle;

a minimum peak detector that detects a minimum, peak of the inputsignal; and

an adjacent peak detector that detects positions of a first maximumpeak, a second maximum peak, and the minimum peak, wherein the firstmaximum peak and the second maximum peak are two maximum peaks in theinput signal,

wherein the micro object detection apparatus determines whether or notthe maximum peaks are quasi peaks corresponds to one particle on thebasis of the positions of the maximum peaks and the minimum peak.

<Additional Statement 15>

The micro object detection apparatus according to additional statement14, comprising: an adjacent peak detector that detects whether or notthe minimum peak exists between the first maximum peak and the secondmaximum peak, in the order of detection in the maximum peak detector andthe minimum peak detector.

<Additional Statement 16>

The micro object detection apparatus according to additional statement14, comprising: an adjacent peak detector that detects whether or notthe maximum peak detector and the minimum peak detector detect the firstmaximum peak, the minimum peak, and the second maximum peak in thisorder.

<Additional Statement 17>

The micro object detection apparatus according to any one of additionalstatements 14 to 16, comprising: a peak difference determination unitthat determines whether or not the first max mum peak and the secondmaximum peak detected by the maximum peak detector are quasi peakscorresponds to one particle.

<Additional Statement 18>

The micro object detection apparatus according to additional statement17, wherein the peak difference determination unit determines whether ornot the first maximum peak and the second maximum peak are the quasipeaks, on the basis of comparison between the first maximum peak and theminimum peak or comparison between the second maximum peak and theminimum peak.

<Additional Statement 19>

The micro object detection apparatus according to additional statement17, wherein the peak difference determination unit determines whether ornot the first maximum peak and the second maximum peak are the quasipeaks, on the basis of comparison between a value calculated on thebasis of the first maximum peak and the second maximum peak and theminimum peak.

<Additional Statement 20>

The micro object detection apparatus according to additional statement18 or 19, wherein the comparison is a difference between two values.

<Additional Statement 21>

The micro object detection apparatus according to additional statement18 or 19, wherein the comparison is a rate between two values.

<Additional Statement 22>

The micro object detection apparatus according to any one of additionalstatements 13 to 21, comprising: a quasi peak elimination unit thatoutputs a result indicating that there is one particle, when it isdetermined that the maximum peaks are the quasi peaks, and outputs aresult indicating that there are two particles, when the peak differencedetermination unit determines that the maximum peaks are not the quasipeaks.

<Additional Statement 23>

The micro object detection apparatus according to any one of additionalstatements 13 to 22, comprising: a counter that counts the number ofparticles.

<Additional Statement 24>

The micro object detection apparatus according to any one of additionalstatements 13 to 23, wherein the micro object detection apparatuscalculates a number concentration or a weight concentration of theparticles, on the basis of the number of particles.

<Additional Statement (4)>

<Additional Statement 1>.

A micro object detection apparatus comprising:

a first optical system that includes a first reflection region, a secondreflection region, and a first light reception element, and directsscattered light scattered when irradiation light hits a particle, to thefirst light reception element, by reflecting the scattered light by thefirst reflection region and the second reflection region; and

a second optical system that receives the scattered light,

wherein the scattered light is directed to the first light receptionelement by providing a first passage region in the second reflectionregion, and

the scattered light is directed to the second optical system byproviding a second passage region in the first reflection region.

<Additional Statement 2>

The micro object detection apparatus according to additional statement1, wherein the second passage region includes a region surrounded by aperiphery shape of the first passage region projected on the firstreflection region by the scattered light.

<Additional Statement 3>

The micro object detection apparatus according to additional statement 1or 2, wherein the second passage region is located at a positionopposite to the first passage region.

<Additional Statement 4>

The micro object detection apparatus according to any one of additionalstatements 1 to 3, wherein the first passage region is a hole providedin the second reflection region.

<Additional Statement 5>

The micro object detection apparatus according to any one of additionalstatements 1 to 4, wherein the second passage region is a hole providedin the first reflection region.

<Additional Statement 6>

The micro object detection apparatus according to any one of additionalstatements 1 to 7, wherein the second passage region is positionedinside a region surrounded by a periphery shape of the first passageregion projected on the first reflection region by the scattered light.

<Additional Statement 7>

The micro object detection apparatus according to any one of additionalstatements 1 to 6, wherein the micro object detection apparatusdetermines a type of the particle, on the basis of an intensity of thescattered light detected by the first light reception element.

<Additional Statement 8>

The micro object detection apparatus according to any one of additionalstatements 1 to 7, wherein the micro object detection apparatusdetermines whether or not the particle is a particulate matter, on thebasis of an intensity of the scattered light detected by the first lightreception element.

<Additional Statement 9>

The micro object detection apparatus according to any one of additionalstatements 1 to 8, wherein the micro object detection apparatusdetermines whether or not the particle is a micro particulate matter, onthe basis of an intensity of the scattered light detected by the firstlight reception element.

<Additional Statement 10>

The micro object detection apparatus according to any one of additionalstatements 1 to 9, comprising: a particle type determination unit thatdetermines a type of the particle.

<Additional Statement 11>

The micro object detection apparatus according to any one of additionalstatements 1 to 10, wherein the first reflection region has anellipsoidal shape, and reflects the scattered light coming from theparticle to direct the scattered light to the first light receptionelement, by utilizing two focal point positions of the ellipsoidalshape.

<Additional Statement 12>

The micro object detection apparatus according to additional statement11, wherein the particle is positioned in a region of a first focalpoint of the first reflection region.

<Additional Statement 13>

The micro object detection apparatus according to additional statement11 or 12, wherein the first light reception element is positioned in aregion of a second focal point of the first reflection region.

<Additional Statement 14>

The micro object detection apparatus according to any one of additionalstatements 1 to 13, wherein the second reflection region reflects thescattered light coming from the particle to direct the scattered lightto the first reflection region, and the scattered light is reflected bythe first reflection region and is directed to the first light receptionelement.

<Additional Statement 15>

The micro object detection apparatus according to any one of additionalstatements 1 to 14, wherein the second reflection region has a sphericalshape.

<Additional Statement 16>

The micro object detection apparatus according to any one of additionalstatements 1 to 25, wherein the second reflection region is a sphericalmirror.

<Additional Statement 17>

The micro object detection apparatus according to additional statement15 or 16, wherein a third focal point of the second reflection region ispositioned at a position of the first focal point.

<Additional Statement 18>

The micro object detection apparatus according to any one of additionalstatements 1 to 14, wherein the second reflection region has anaspherical shape based on a spherical shape.

<Additional Statement 19>

The micro object detection apparatus according to any one of additionalstatements 1 to 14 and 18, wherein the second reflection region is anaspherical mirror based on a spherical shape.

<Additional Statement 20>

The micro object detection apparatus according to additional statement18 or 19, wherein a third focal point of the second reflection region ispositioned at a position of the first focal point.

<Additional Statement 21>

The micro object detection apparatus according to any one of additionalstatements 18 to 20, wherein a light flux diameter of the scatteredlight reflected by the second reflection region is larger than a lightflux diameter of the scattered light of a case where the scattered lightis reflected by the reflection region having the spherical shape as abasis for the aspherical shape, at a position of the particle at whichthe scattered light is generated.

<Additional Statement 22>

The micro object detection apparatus according to any one of additionalstatements 1 to 14 and 18 to 21, wherein the second reflection regiongenerates a plurality of focal points to disperse the focal points.

<Additional Statement 23>

The micro object detection apparatus according to any one of additionalstatements 1 to 14 and 18 to 22, wherein the second reflection regiongenerates spherical aberration.

<Additional Statement 24>

The micro object detection apparatus according to additional statement23, wherein the spherical aberration generated by the second reflectionregion is equal to or larger than 0.07 λrms.

<Additional Statement 25>

The micro object detection apparatus according to additional statement23, wherein the spherical aberration generated by the second reflectionregion is equal to or larger than 6 λpv.

<Additional Statement 26>

The micro object detection apparatus according to any one of additionalstatements 23 to 25, wherein the spherical aberration generated by thesecond reflection region is equal to or smaller than 30 λpv.

<Additional Statement 27>

The micro object detection apparatus according to any one of additionalstatements 23 to 25, wherein the spherical aberration generated by thesecond reflection region is equal to or smaller than 50 λpv.

<Additional Statement 28>

The micro object detection apparatus according to any one of additionalstatements 1 to 27, wherein the first optical system detects lighthaving a different wavelength from a wavelength of the irradiationlight, among the scattered light.

<Additional Statement 29>

The micro object detection apparatus according to any one of additionalstatements 1 to 28, wherein the first optical system detectsfluorescence included in the scattered light.

<Additional Statement 30>

The micro object detection apparatus according to any one of additionalstatements 1 to 29, wherein the second optical system separates thescattered light directed to the second optical system into differentpolarized light components, and detects intensities of the separatedscattered light.

<Additional Statement 31>

The micro object detection apparatus according to additional statement30, wherein the second optical system includes a polarized lightseparating element that separates the scattered light into the polarizedlight components.

<Additional Statement 32>

The micro object detection apparatus according to additional statement31, wherein the polarized light separating element is a polarizationprism.

<Additional Statement 33>

The micro object detection apparatus according to any one of additionalstatements 30 to 32, wherein the second optical system includes a secondlight reception element and a third light reception element that receivethe scattered light separated into the polarized light components.

<Additional Statement 34>

The micro object detection apparatus according to additional statement33, wherein

the second light reception element receives the scattered light of afirst polarized light component, and

the third light reception element receives the scattered light of asecond polarized light component that is orthogonal to the scatteredlight of the first polarized light component.

<Additional Statement 35>

The micro object detection apparatus according to additional statement33 or 34, wherein the second optical system includes a first lightconverging element that converges the scattered light toward the secondlight reception element and the third light reception element.

<Additional Statement 36>

The micro object detection apparatus according to additional statement35, wherein the first light converging element is a first converginglens,

<Additional Statement 37>

The micro object detection apparatus according to any one of additionalstatements 30 to 36, wherein the micro object detection apparatusdetermines a type of the particle, on the basis of the intensities ofthe scattered light detected by the second optical system.

<Additional Statement 38>

The micro object detection apparatus according to any one of additionalstatements 30 to 37, wherein the micro object detection apparatusdetermines whether the particle is a spherical shape or other than aspherical shape, on the basis of the intensities of the scattered lightseparated into the polarized light components.

<Additional Statement 39>

The micro object detection apparatus according to any one of additionalstatements 30 to 38, wherein the micro object detection apparatusdetermines that a shape of the particle is a spherical shape, whendetecting that the intensities of the scattered light separated into thepolarized light components are the same value.

<Additional Statement 40>

The micro object detection apparatus according to any one of additionalstatements 30 to 39, wherein the micro object detection apparatusdetermines that a shape of the particle is other than a spherical shapewhen detecting that the intensities of the scattered light separatedinto the polarized light components are different, values.

<Additional Statement 41>

The micro object detection apparatus according to any one of additionalstatements 30 to 40, wherein the particle type determination unitdetermines that the particle is pollen, when detecting that theintensities of the scattered light separated by the second opticalsystem are the same value.

<Additional Statement 42>

The micro object detection apparatus according to any one of additionalstatements 30 to 41, wherein the particle type determination unitdetermines that the particle is dust, when detecting that theintensities of the scattered light separated by the second opticalsystem are different values.

<Additional Statement 43>

The micro object, detection apparatus according to any one of additionalstatements 30 to 42, comprising: a particle type determination unit thatdetermines a type of the particle.

<Additional Statement 44>

The micro object detection apparatus according to any one of additionalstatements 1 to 43, wherein the micro object detection apparatus detectsa maximum peak of an intensity of the scattered light output from thefirst optical system.

<Additional Statement 45>

The micro object detection apparatus according to any one of additionalstatements 1 to 44, wherein the micro object detection apparatus detectsa maximum peak of an intensity of the scattered light output from thesecond optical system.

<Additional Statement 46>

The micro object, detection apparatus according to any one of additionalstatements 1 to 45, comprising: a maximum peak detector that detects amaximum peak of an intensity of the scattered light.

<Additional Statement 47>

The micro object detection apparatus according to additional statement44, wherein the micro object detection apparatus detects a minimum peakof the intensity of the scattered light output from the first opticalsystem.

<Additional Statement 48>

The micro object detection apparatus according to additional statement45, wherein the micro object detection apparatus detects a minimum peakof the intensity of the scattered light output from the second opticalsystem.

<Additional Statement 49>

The micro object detection apparatus according to any one of additionalstatements 1 to 48, comprising: a minimum peak detector that detects aminimum peak of an intensity of the scattered light.

<Additional Statement 50>

The micro object detection apparatus according to additional statement47, wherein

two maximum peaks detected from the first optical system are a firstmaximum peak and a second maximum peak, and

the macro object detection apparatus determines whether or not the firstmaximum peak and the second maximum peak are quasi peaks correspondingto one particle.

<Additional Statement 51>

The micro object detection apparatus according to additional statement48, wherein

two maximum peaks detected from the second optical system are a firstmaximum peak and a second maximum peak, and

the micro object detection apparatus determines whether or not the firstmaximum peak and the second maximum peak are quasi peaks correspondingto one particle.

<Additional Statement 52>

The micro object detection apparatus according to additional statement50 or 51, comprising: a peak difference determination unit thatdetermines whether or not the quasi peaks exist.

<Additional Statement 53>

The micro object detection apparatus according to any one of additionalstatements 1 to 49, comprising: a peak difference determination unitthat determines whether or not a quasi peak exists.

<Additional Statement 54>

The micro object detection apparatus according to any one of additionalstatements 50 to 52, wherein the micro object detection apparatusdetermines whether or not the first maximum peak and the second maximumpeak are the quasi peaks, on the basis of comparison between the firstmaximum peak and the minimum peak or comparison between the secondmaximum peak and the minimum peak.

<Additional Statement 55>

The micro object detection apparatus according to any one of additionalstatements 50 to 52, wherein the micro object detection apparatusdetermines whether or not the first maximum peak and the second maximumpeak are the quasi peaks, on the basis of comparison between a valuecalculated on the basis of the first maximum peak and the second maximumpeak and the minimum peak.

<Additional Statement 56>

The micro object detection apparatus according to additional statement54 or 55, wherein the comparison is a difference between two values.

<Additional Statement 57>

The micro object detection apparatus according to additional statement54 or 55, wherein the comparison is a rate between two values.

<Additional Statement 58>

The macro object detection apparatus according to any one of additionalstatements 50 to 52 and additional statements 54 to 57, wherein themicro object detection apparatus determines whether or not the quasipeaks exist, on the basis of an order of detection of the maximum peaksand the minimum peak.

<Additional Statement 59>

The micro object detect on apparatus according to any one of additionalstatements 50 to 52 and additional statements 54 to 58, wherein themicro object detection apparatus determines that the quasi peaks exist,when the first maximum peak, the minimum peak, and the second maximumpeak are detected in this order.

<Additional Statement 60>

The micro object detection apparatus according to any one of additionalstatements 50 to 52 and additional statements 54 to 59, comprising: anadjacent peak determination unit that determines whether or not theminimum peak exists between the first maximum peak and the secondmaximum peak.

<Additional Statement 61>

The micro object, detection apparatus according to any one of additionalstatements 1 to 49 and additional statement 53, comprising: an adjacentpeak determination unit that determines whether or not a minimum peakexists between a first maximum peak and a second maximum peak.

<Additional Statement 62>

The micro object detection apparatus according to any one of additionalstatements 58 to 60, wherein the micro object detection apparatusdetermines that there is one particle, when determining that the quasipeaks exist, and that there are two particles, when determining that thequasi peaks do not exist.

<Additional Statement 63>

The micro object detection apparatus according to any one of additionalstatements 58 to 60, comprising: a quasi peak elimination unit thatoutputs a result indicating that, there is one particle, whendetermining that the quasi peaks exist, and outputs a result indicatingthat there are two particles, when determining that the quasi peaks donot exist.

<Additional Statement 64>

The micro object detection apparatus according to any one of additionalstatements 1 to 57, comprising: a quasi peak elimination unit thatoutputs a result indicating that there is one particle, when determiningthat quasi peaks exist, and outputs a result indicating that there aretwo particles, when determining that the quasi peaks do not exist.

<Additional Statement 65>

The micro object detection apparatus according to additional statement62, wherein the micro object detection apparatus counts the number ofparticles, on the basis of a determination result of the quasi peaks.

<Additional Statement 66>

The micro object detection apparatus according to additional statement63 or 64, wherein the micro object detection apparatus counts the numberof particles output by the quasi peak elimination unit.

<Additional Statement 67>

The micro object detection apparatus according to any one of additionalstatements 1 to 66, wherein the micro object detection apparatus countsthe number of particles, on the basis of an intensity of the scatteredlight detected by the first optical system and the second opticalsystem.

<Additional Statement 68>

The micro object detection apparatus according to any one of additionalstatements 1 to 67, comprising: a counter that counts the number ofparticles.

<Additional Statement 69>

The micro object detection apparatus according to any one of additionalstatements 1 to 68, wherein the micro object detection apparatuscalculates a number concentration or a weight concentration of theparticles, on the basis of the calculated number of particles.

<Additional Statement 70>

The micro object detection apparatus according to any one of additionalstatements 1 to 69, comprising: a light radiation unity that radiatesthe irradiation light on the particle.

<Additional Statement 71>

The micro object detection apparatus according to additional statement70, wherein the light radiation unit includes a light source thatradiates the irradiation light.

<Additional Statement 72>

The micro object detection apparatus according to additional statement70 or 71, wherein the light radiation unit includes a second lightconverging element that converges the irradiation light,

<Additional Statement 73>

The micro object detection apparatus according to additional statement72, wherein the second light converging element is a second converginglens,

<Additional Statement 74>

The micro object detection apparatus according to additional statement72 or 73, wherein the light radiation unit includes a holding unit thatholds at least one of the light source and the second light convergingelement.

<Additional Statement 75>

The micro object detection apparatus according to additional statement74, wherein the holding unit is connected to the first optical system.

DESCRIPTION OF REFERENCE CHARACTERS

11, 12, 13 micro object detection apparatus, 500, 520 optical system ofmicro object detection apparatus, 50, 51, 52, 53 detection opticalsystem, 52 a, 53 a first detection optical system, 52 b, 53 b seconddetection optical system, 10 laser light radiation unit, 20 scatteredlight receiving unit, 1 Laser light emitting element, 2 lens, 3irradiation light, 4 beam trap, 5 a suction port, 5 b discharge port, 6light reception element, 60, 65, 70 detection circuit unit, 61, 61 a, 61b, 61 c amplifier circuit, 62, 62 a, 62 b, 62 c, 71 maximum peakdetector, 63 peak number counter, 64 particle type determination unit,72 minimum peak detector, 73 adjacent peak determination unit, 74 peakdifference determination unit, 75 quasi peak elimination unit, 76 peakdetector, 80 particle determination unit, 91 radiation unit holder, 101,103 first converging mirror, 102, 104 second converging mirror, 101 a,102 a, 103 a, 104 a reflection surface, 111 a, 111 b light beam on firstpath, 112 light beam on second path, 113 a, 113 b, 113 c, 113 d, 113 elight beam on third path, 114, 114 p, 114 s light beam on fourth path,160 lens, 161, 162 light reception element, 163 polarization prism, 163p, 163 s projection surface, 164 reflection surface, 165 lens portion,200 scattered light, 300 parallel flat plate, A output value of signalS₁, Ap, Ap₁, Ap₂, Ap₃, Ap₄, Ap₅, Ap₆ peak point, AP opening, D detectionregion, DL hole, ds distance, Ip, Is light intensity, P passage region,P₁, P₂, P₃, P₄, P₅, P₆ peak value, ΔP₁, Δp₂, Δp₅ value, F₁, F₂, F₃waveform, G₁, G₂ position, R particle, D detection region, P passageregion, L scattered light, Ls lateral scattered light, Lfs forwardscattered light, Lbs backward scattered light, r₂, r₃ radius, S₁, S₁₁,S₁₂, S₁₃, S₂, S₂₁, S₂₂, S₂₃, S₃, S₃₁, S₃₂, S₃₃, S₄, S₅, S₆, S₇ signal,to center of waveform, O center axis of design of second convergingmirror 102, H passage hole U₁, U₂, U₃ focal point position, λe, λfwavelength.

What is claimed is:
 1. A micro object detection apparatus comprising: afirst optical system that includes a first reflection region, a secondreflection region, and a first light reception element, the firstoptical system directing light scattered when irradiation light hits aparticle, to the first light reception element, by reflecting thescattered light by the first reflection region and the second reflectionregion, wherein the second reflection region reflects the lightscattered from the particle to direct this scattered light to the firstreflection region, this scattered light being further reflected by thefirst reflection region and directed to the first light receptionelement; and a second optical system that receives the scattered light,wherein the scattered light is directed to the first light receptionelement by providing a first passage region in the second reflectionregion and is directed to the second optical system by providing asecond passage region in the first reflection region, and the secondpassage region is located to face the first passage region.
 2. The microobject detection apparatus according to claim 1, wherein the secondoptical system separates the scattered light directed to the secondoptical system into different polarized light components, and detectsintensities of the separated scattered light.
 3. The micro objectdetection apparatus according to claim 2, wherein the first reflectionregion has an ellipsoidal shape, and reflects the scattered light comingfrom the particle to direct the scattered light to the first lightreception element, by utilizing two focal point positions of theellipsoidal shape.
 4. The micro object detection apparatus according toclaim 2, wherein the micro object detection apparatus determines whetherthe particle is a spherical shape or other than a spherical shape, onthe basis of the intensities of the scattered light separated into thepolarized light components.
 5. The micro object detection apparatusaccording to claim 1, wherein the second reflection region has aspherical shape.
 6. The micro object detection apparatus according toclaim 1, wherein the first optical system detects light having adifferent wavelength from a wavelength of the irradiation light, amongthe scattered light.
 7. The micro object detection apparatus accordingto claim 6, wherein the first optical system detects fluorescenceincluded in the scattered light.
 8. The micro object detection apparatusaccording to claim 7, wherein the second reflection region has aspherical shape.
 9. The micro object detection apparatus according toclaim 6, wherein the first reflection region has an ellipsoidal shape,and reflects the scattered light coming from the particle to direct thescattered light to the first light reception element, by utilizing twofocal point positions of the ellipsoidal shape.
 10. The micro objectdetection apparatus according to claim 6, wherein the second opticalsystem detects intensities of the scattered light.
 11. The micro objectdetection apparatus according to claim 1, wherein the second opticalsystem detects light having a different wavelength from a wavelength ofthe irradiation light, among the scattered light.
 12. The micro objectdetection apparatus according to claim 11, wherein the second reflectionregion has a spherical shape.
 13. The micro object detection apparatusaccording to claim 11, wherein the second optical system detectsfluorescence included in the scattered light.
 14. The micro objectdetection apparatus according to claim 11, wherein the first reflectionregion has an ellipsoidal shape, and reflects the scattered light comingfrom the particle to direct the scattered light to the first lightreception element, by utilizing two focal point positions of theellipsoidal shape.